[PATCH v5 00/15] allow BFLT executables on systems with a MMU

[PATCH v5 00/15] allow BFLT executables on systems with a MMU

[Nicolas Pitre]

This series provides the necessary changes to allow "flat" executable
binaries meant for no-MMU systems to actually run on systems with a MMU.
Also thrown in are various cleanups to binfmt_flat.c.

This can also be found in the following git repo:

	git://git.linaro.org/people/nicolas.pitre/linux binfmt_flat_with_mmu

*Why?*

Because developing and testing natively on a large system with lots of
RAM makes it so much more convenient to use all the existing profiling
tools and debugging facilities that a kernel with lots of RAM can give.
And incidentally, those systems with lots of RAM all have a MMU.

*Why not use elf_fdpic?*

The flat executable format is simple with very small footprint
overhead, either in the executables themselves or kernel support.
This makes the flat format more suitable than elf_fdpic for very small
single user-app embedded systems.

And while elf_fdpic binaries can run on MMU systems, flat binaries still
couldn't, which just felt wrong.

So here it is. The no-MMU support should remain unaffected, confirmed by
Greg Ungerer. Tested with MMU on ARM and M68K.

Changes since v4:

- Isolated architecture specific changes in their own patches for easier
  review through their own path to mainline.

- Added needed m68k register fixup from Greg Ungerer.

Changes since v3:

- Small cosmetic changes to pr_*().

- Addressed most important checkpatch complaints on the whole source file
  and patches in this seris.

Changes since  v2:

- Added protection against a corrupted header that could have caused nasty
  overflows etc. Suggested by Alan Cox.

- printk() modernization. Suggested by Greg Ungerer / Geert Uytterhoeven.

- Added Greg Ungerer's reviewed-by tag.

Changes since v1:

- Removed SuperH and Xtensa from the Kconfig rule as they fail to build
  due to lack of get/put_unaligned_user().

- Clarified some commit logs a bit.

diffstat:

 arch/arm/include/asm/flat.h       |   5 +-
 arch/m68k/include/asm/flat.h      |  11 +-
 arch/m68k/include/asm/processor.h |   2 -
 fs/Kconfig.binfmt                 |   3 +-
 fs/binfmt_elf_fdpic.c             |  38 +--
 fs/binfmt_flat.c                  | 525 ++++++++++++++++++--------------
 fs/exec.c                         |  33 ++
 include/linux/binfmts.h           |   2 +
 8 files changed, 345 insertions(+), 274 deletions(-)

[PATCH v5 01/15] binfmt_flat: assorted cleanups

[Nicolas Pitre]

Remove excessive casts, do some code grouping, fix most important
checkpatch.pl complaints, etc.

No functional changes.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 230 ++++++++++++++++++++++++++-----------------------------
 1 file changed, 109 insertions(+), 121 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index caf9e39bb8..892dba62bf 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -15,7 +15,6 @@
  *	JAN/99 -- coded full program relocation (gerg at snapgear.com)
  */
 
-#include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -25,8 +24,6 @@
 #include <linux/string.h>
 #include <linux/fs.h>
 #include <linux/file.h>
-#include <linux/stat.h>
-#include <linux/fcntl.h>
 #include <linux/ptrace.h>
 #include <linux/user.h>
 #include <linux/slab.h>
@@ -34,10 +31,9 @@
 #include <linux/personality.h>
 #include <linux/init.h>
 #include <linux/flat.h>
-#include <linux/syscalls.h>
+#include <linux/uaccess.h>
 
 #include <asm/byteorder.h>
-#include <asm/uaccess.h>
 #include <asm/unaligned.h>
 #include <asm/cacheflush.h>
 #include <asm/page.h>
@@ -80,7 +76,7 @@ struct lib_info {
 		unsigned long text_len;			/* Length of text segment */
 		unsigned long entry;			/* Start address for this module */
 		unsigned long build_date;		/* When this one was compiled */
-		short loaded;				/* Has this library been loaded? */
+		bool loaded;				/* Has this library been loaded? */
 	} lib_list[MAX_SHARED_LIBS];
 };
 
@@ -107,8 +103,8 @@ static struct linux_binfmt flat_format = {
 static int flat_core_dump(struct coredump_params *cprm)
 {
 	printk("Process %s:%d received signr %d and should have core dumped\n",
-			current->comm, current->pid, (int) cprm->siginfo->si_signo);
-	return(1);
+			current->comm, current->pid, cprm->siginfo->si_signo);
+	return 1;
 }
 
 /****************************************************************************/
@@ -120,11 +116,11 @@ static int flat_core_dump(struct coredump_params *cprm)
 
 static unsigned long create_flat_tables(
 	unsigned long pp,
-	struct linux_binprm * bprm)
+	struct linux_binprm *bprm)
 {
-	unsigned long *argv,*envp;
-	unsigned long * sp;
-	char * p = (char*)pp;
+	unsigned long *argv, *envp;
+	unsigned long *sp;
+	char *p = (char *)pp;
 	int argc = bprm->argc;
 	int envc = bprm->envc;
 	char uninitialized_var(dummy);
@@ -142,7 +138,7 @@ static unsigned long create_flat_tables(
 
 	put_user(argc, sp);
 	current->mm->arg_start = (unsigned long) p;
-	while (argc-->0) {
+	while (argc-- > 0) {
 		put_user((unsigned long) p, argv++);
 		do {
 			get_user(dummy, p); p++;
@@ -150,7 +146,7 @@ static unsigned long create_flat_tables(
 	}
 	put_user((unsigned long) NULL, argv);
 	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
-	while (envc-->0) {
+	while (envc-- > 0) {
 		put_user((unsigned long)p, envp); envp++;
 		do {
 			get_user(dummy, p); p++;
@@ -190,7 +186,7 @@ static int decompress_exec(
 	loff_t fpos;
 	int ret, retval;
 
-	DBG_FLT("decompress_exec(offset=%x,buf=%x,len=%x)\n",(int)offset, (int)dst, (int)len);
+	DBG_FLT("decompress_exec(offset=%lx,buf=%p,len=%lx)\n", offset, dst, len);
 
 	memset(&strm, 0, sizeof(strm));
 	strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
@@ -243,7 +239,7 @@ static int decompress_exec(
 	ret = 10;
 	if (buf[3] & EXTRA_FIELD) {
 		ret += 2 + buf[10] + (buf[11] << 8);
-		if (unlikely(LBUFSIZE <= ret)) {
+		if (unlikely(ret >= LBUFSIZE)) {
 			DBG_FLT("binfmt_flat: buffer overflow (EXTRA)?\n");
 			goto out_free_buf;
 		}
@@ -251,7 +247,7 @@ static int decompress_exec(
 	if (buf[3] & ORIG_NAME) {
 		while (ret < LBUFSIZE && buf[ret++] != 0)
 			;
-		if (unlikely(LBUFSIZE == ret)) {
+		if (unlikely(ret == LBUFSIZE)) {
 			DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
 			goto out_free_buf;
 		}
@@ -259,7 +255,7 @@ static int decompress_exec(
 	if (buf[3] & COMMENT) {
 		while (ret < LBUFSIZE && buf[ret++] != 0)
 			;
-		if (unlikely(LBUFSIZE == ret)) {
+		if (unlikely(ret == LBUFSIZE)) {
 			DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");
 			goto out_free_buf;
 		}
@@ -327,17 +323,17 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 		r &= 0x00ffffff;	/* Trim ID off here */
 	}
 	if (id >= MAX_SHARED_LIBS) {
-		printk("BINFMT_FLAT: reference 0x%x to shared library %d",
-				(unsigned) r, id);
+		printk("BINFMT_FLAT: reference 0x%lx to shared library %d",
+				r, id);
 		goto failed;
 	}
 	if (curid != id) {
 		if (internalp) {
-			printk("BINFMT_FLAT: reloc address 0x%x not in same module "
-					"(%d != %d)", (unsigned) r, curid, id);
+			printk("BINFMT_FLAT: reloc address 0x%lx not in same module "
+					"(%d != %d)", r, curid, id);
 			goto failed;
-		} else if ( ! p->lib_list[id].loaded &&
-				load_flat_shared_library(id, p) < 0) {
+		} else if (!p->lib_list[id].loaded &&
+			   load_flat_shared_library(id, p) < 0) {
 			printk("BINFMT_FLAT: failed to load library %d", id);
 			goto failed;
 		}
@@ -358,8 +354,8 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 	text_len = p->lib_list[id].text_len;
 
 	if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
-		printk("BINFMT_FLAT: reloc outside program 0x%x (0 - 0x%x/0x%x)",
-		       (int) r,(int)(start_brk-start_data+text_len),(int)text_len);
+		printk("BINFMT_FLAT: reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
+		       r, start_brk-start_data+text_len, text_len);
 		goto failed;
 	}
 
@@ -369,7 +365,7 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 		addr = r - text_len + start_data;
 
 	/* Range checked already above so doing the range tests is redundant...*/
-	return(addr);
+	return addr;
 
 failed:
 	printk(", killing %s!\n", current->comm);
@@ -383,11 +379,11 @@ failed:
 static void old_reloc(unsigned long rl)
 {
 #ifdef DEBUG
-	char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
+	static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
 #endif
 	flat_v2_reloc_t	r;
 	unsigned long *ptr;
-	
+
 	r.value = rl;
 #if defined(CONFIG_COLDFIRE)
 	ptr = (unsigned long *) (current->mm->start_code + r.reloc.offset);
@@ -397,10 +393,10 @@ static void old_reloc(unsigned long rl)
 
 #ifdef DEBUG
 	printk("Relocation of variable at DATASEG+%x "
-		"(address %p, currently %x) into segment %s\n",
-		r.reloc.offset, ptr, (int)*ptr, segment[r.reloc.type]);
+		"(address %p, currently %lx) into segment %s\n",
+		r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);
 #endif
-	
+
 	switch (r.reloc.type) {
 	case OLD_FLAT_RELOC_TYPE_TEXT:
 		*ptr += current->mm->start_code;
@@ -417,27 +413,25 @@ static void old_reloc(unsigned long rl)
 	}
 
 #ifdef DEBUG
-	printk("Relocation became %x\n", (int)*ptr);
+	printk("Relocation became %lx\n", *ptr);
 #endif
-}		
+}
 
 /****************************************************************************/
 
-static int load_flat_file(struct linux_binprm * bprm,
+static int load_flat_file(struct linux_binprm *bprm,
 		struct lib_info *libinfo, int id, unsigned long *extra_stack)
 {
-	struct flat_hdr * hdr;
-	unsigned long textpos = 0, datapos = 0, result;
-	unsigned long realdatastart = 0;
-	unsigned long text_len, data_len, bss_len, stack_len, flags;
-	unsigned long full_data;
-	unsigned long len, memp = 0;
-	unsigned long memp_size, extra, rlim;
-	unsigned long *reloc = 0, *rp;
+	struct flat_hdr *hdr;
+	unsigned long textpos, datapos, realdatastart;
+	unsigned long text_len, data_len, bss_len, stack_len, full_data, flags;
+	unsigned long len, memp, memp_size, extra, rlim;
+	unsigned long *reloc, *rp;
 	struct inode *inode;
-	int i, rev, relocs = 0;
+	int i, rev, relocs;
 	loff_t fpos;
 	unsigned long start_code, end_code;
+	ssize_t result;
 	int ret;
 
 	hdr = ((struct flat_hdr *) bprm->buf);		/* exec-header */
@@ -478,11 +472,11 @@ static int load_flat_file(struct linux_binprm * bprm,
 		ret = -ENOEXEC;
 		goto err;
 	}
-	
+
 	/* Don't allow old format executables to use shared libraries */
 	if (rev == OLD_FLAT_VERSION && id != 0) {
-		printk("BINFMT_FLAT: shared libraries are not available before rev 0x%x\n",
-				(int) FLAT_VERSION);
+		printk("BINFMT_FLAT: shared libraries are not available before rev 0x%lx\n",
+				FLAT_VERSION);
 		ret = -ENOEXEC;
 		goto err;
 	}
@@ -517,11 +511,9 @@ static int load_flat_file(struct linux_binprm * bprm,
 
 	/* Flush all traces of the currently running executable */
 	if (id == 0) {
-		result = flush_old_exec(bprm);
-		if (result) {
-			ret = result;
+		ret = flush_old_exec(bprm);
+		if (ret)
 			goto err;
-		}
 
 		/* OK, This is the point of no return */
 		set_personality(PER_LINUX_32BIT);
@@ -549,38 +541,38 @@ static int load_flat_file(struct linux_binprm * bprm,
 		textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
 				  MAP_PRIVATE|MAP_EXECUTABLE, 0);
 		if (!textpos || IS_ERR_VALUE(textpos)) {
-			if (!textpos)
-				textpos = (unsigned long) -ENOMEM;
-			printk("Unable to mmap process text, errno %d\n", (int)-textpos);
 			ret = textpos;
+			if (!textpos)
+				ret = -ENOMEM;
+			printk("Unable to mmap process text, errno %d\n", ret);
 			goto err;
 		}
 
 		len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
 		len = PAGE_ALIGN(len);
-		realdatastart = vm_mmap(0, 0, len,
+		realdatastart = vm_mmap(NULL, 0, len,
 			PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);
 
 		if (realdatastart == 0 || IS_ERR_VALUE(realdatastart)) {
+			ret = realdatastart;
 			if (!realdatastart)
-				realdatastart = (unsigned long) -ENOMEM;
-			printk("Unable to allocate RAM for process data, errno %d\n",
-					(int)-realdatastart);
+				ret = -ENOMEM;
+			printk("Unable to allocate RAM for process data, "
+			       "errno %d\n", ret);
 			vm_munmap(textpos, text_len);
-			ret = realdatastart;
 			goto err;
 		}
 		datapos = ALIGN(realdatastart +
 				MAX_SHARED_LIBS * sizeof(unsigned long),
 				FLAT_DATA_ALIGN);
 
-		DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
-				(int)(data_len + bss_len + stack_len), (int)datapos);
+		DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%ld bytes): %lx\n",
+			data_len + bss_len + stack_len, datapos);
 
 		fpos = ntohl(hdr->data_start);
 #ifdef CONFIG_BINFMT_ZFLAT
 		if (flags & FLAT_FLAG_GZDATA) {
-			result = decompress_exec(bprm, fpos, (char *) datapos, 
+			result = decompress_exec(bprm, fpos, (char *)datapos,
 						 full_data, 0);
 		} else
 #endif
@@ -589,29 +581,30 @@ static int load_flat_file(struct linux_binprm * bprm,
 					full_data);
 		}
 		if (IS_ERR_VALUE(result)) {
-			printk("Unable to read data+bss, errno %d\n", (int)-result);
+			ret = result;
+			printk("Unable to read data+bss, errno %d\n", ret);
 			vm_munmap(textpos, text_len);
 			vm_munmap(realdatastart, len);
-			ret = result;
 			goto err;
 		}
 
-		reloc = (unsigned long *) (datapos+(ntohl(hdr->reloc_start)-text_len));
+		reloc = (unsigned long *)
+			(datapos + (ntohl(hdr->reloc_start) - text_len));
 		memp = realdatastart;
 		memp_size = len;
 	} else {
 
 		len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
 		len = PAGE_ALIGN(len);
-		textpos = vm_mmap(0, 0, len,
+		textpos = vm_mmap(NULL, 0, len,
 			PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
 
 		if (!textpos || IS_ERR_VALUE(textpos)) {
-			if (!textpos)
-				textpos = (unsigned long) -ENOMEM;
-			printk("Unable to allocate RAM for process text/data, errno %d\n",
-					(int)-textpos);
 			ret = textpos;
+			if (!textpos)
+				ret = -ENOMEM;
+			printk("Unable to allocate RAM for process text/data, "
+			       "errno %d\n", ret);
 			goto err;
 		}
 
@@ -629,10 +622,10 @@ static int load_flat_file(struct linux_binprm * bprm,
 		 * load it all in and treat it like a RAM load from now on
 		 */
 		if (flags & FLAT_FLAG_GZIP) {
-			result = decompress_exec(bprm, sizeof (struct flat_hdr),
-					 (((char *) textpos) + sizeof (struct flat_hdr)),
+			result = decompress_exec(bprm, sizeof(struct flat_hdr),
+					 (((char *)textpos) + sizeof(struct flat_hdr)),
 					 (text_len + full_data
-						  - sizeof (struct flat_hdr)),
+						  - sizeof(struct flat_hdr)),
 					 0);
 			memmove((void *) datapos, (void *) realdatastart,
 					full_data);
@@ -641,8 +634,7 @@ static int load_flat_file(struct linux_binprm * bprm,
 			if (!IS_ERR_VALUE(result))
 				result = decompress_exec(bprm, text_len, (char *) datapos,
 						 full_data, 0);
-		}
-		else
+		} else
 #endif
 		{
 			result = read_code(bprm->file, textpos, 0, text_len);
@@ -652,21 +644,19 @@ static int load_flat_file(struct linux_binprm * bprm,
 						   full_data);
 		}
 		if (IS_ERR_VALUE(result)) {
-			printk("Unable to read code+data+bss, errno %d\n",(int)-result);
+			ret = result;
+			printk("Unable to read code+data+bss, errno %d\n", ret);
 			vm_munmap(textpos, text_len + data_len + extra +
 				MAX_SHARED_LIBS * sizeof(unsigned long));
-			ret = result;
 			goto err;
 		}
 	}
 
-	if (flags & FLAT_FLAG_KTRACE)
-		printk("Mapping is %x, Entry point is %x, data_start is %x\n",
-			(int)textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
+	start_code = textpos + sizeof(struct flat_hdr);
+	end_code = textpos + text_len;
+	text_len -= sizeof(struct flat_hdr); /* the real code len */
 
 	/* The main program needs a little extra setup in the task structure */
-	start_code = textpos + sizeof (struct flat_hdr);
-	end_code = textpos + text_len;
 	if (id == 0) {
 		current->mm->start_code = start_code;
 		current->mm->end_code = end_code;
@@ -684,16 +674,14 @@ static int load_flat_file(struct linux_binprm * bprm,
 		current->mm->context.end_brk = memp + memp_size - stack_len;
 	}
 
-	if (flags & FLAT_FLAG_KTRACE)
-		printk("%s %s: TEXT=%x-%x DATA=%x-%x BSS=%x-%x\n",
-			id ? "Lib" : "Load", bprm->filename,
-			(int) start_code, (int) end_code,
-			(int) datapos,
-			(int) (datapos + data_len),
-			(int) (datapos + data_len),
-			(int) (((datapos + data_len + bss_len) + 3) & ~3));
-
-	text_len -= sizeof(struct flat_hdr); /* the real code len */
+	if (flags & FLAT_FLAG_KTRACE) {
+		printk("Mapping is %lx, Entry point is %x, data_start is %x\n",
+		       textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
+		printk("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
+		       id ? "Lib" : "Load", bprm->filename,
+		       start_code, end_code, datapos, datapos + data_len,
+		       datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
+	}
 
 	/* Store the current module values into the global library structure */
 	libinfo->lib_list[id].start_code = start_code;
@@ -703,7 +691,7 @@ static int load_flat_file(struct linux_binprm * bprm,
 	libinfo->lib_list[id].loaded = 1;
 	libinfo->lib_list[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
 	libinfo->lib_list[id].build_date = ntohl(hdr->build_date);
-	
+
 	/*
 	 * We just load the allocations into some temporary memory to
 	 * help simplify all this mumbo jumbo
@@ -743,14 +731,16 @@ static int load_flat_file(struct linux_binprm * bprm,
 	 */
 	if (rev > OLD_FLAT_VERSION) {
 		unsigned long persistent = 0;
-		for (i=0; i < relocs; i++) {
+		for (i = 0; i < relocs; i++) {
 			unsigned long addr, relval;
 
-			/* Get the address of the pointer to be
-			   relocated (of course, the address has to be
-			   relocated first).  */
+			/*
+			 * Get the address of the pointer to be
+			 * relocated (of course, the address has to be
+			 * relocated first).
+			 */
 			relval = ntohl(reloc[i]);
-			if (flat_set_persistent (relval, &persistent))
+			if (flat_set_persistent(relval, &persistent))
 				continue;
 			addr = flat_get_relocate_addr(relval);
 			rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
@@ -780,14 +770,14 @@ static int load_flat_file(struct linux_binprm * bprm,
 			}
 		}
 	} else {
-		for (i=0; i < relocs; i++)
+		for (i = 0; i < relocs; i++)
 			old_reloc(ntohl(reloc[i]));
 	}
-	
+
 	flush_icache_range(start_code, end_code);
 
 	/* zero the BSS,  BRK and stack areas */
-	memset((void*)(datapos + data_len), 0, bss_len + 
+	memset((void *)(datapos + data_len), 0, bss_len +
 			(memp + memp_size - stack_len -		/* end brk */
 			libinfo->lib_list[id].start_brk) +	/* start brk */
 			stack_len);
@@ -846,7 +836,7 @@ out:
 	allow_write_access(bprm.file);
 	fput(bprm.file);
 
-	return(res);
+	return res;
 }
 
 #endif /* CONFIG_BINFMT_SHARED_FLAT */
@@ -857,7 +847,7 @@ out:
  * libraries.  There is no binary dependent code anywhere else.
  */
 
-static int load_flat_binary(struct linux_binprm * bprm)
+static int load_flat_binary(struct linux_binprm *bprm)
 {
 	struct lib_info libinfo;
 	struct pt_regs *regs = current_pt_regs();
@@ -869,6 +859,7 @@ static int load_flat_binary(struct linux_binprm * bprm)
 	int i, j;
 
 	memset(&libinfo, 0, sizeof(libinfo));
+
 	/*
 	 * We have to add the size of our arguments to our stack size
 	 * otherwise it's too easy for users to create stack overflows
@@ -881,33 +872,33 @@ static int load_flat_binary(struct linux_binprm * bprm)
 	stack_len += (bprm->argc + 1) * sizeof(char *); /* the argv array */
 	stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
 	stack_len += FLAT_STACK_ALIGN - 1;  /* reserve for upcoming alignment */
-	
+
 	res = load_flat_file(bprm, &libinfo, 0, &stack_len);
 	if (res < 0)
 		return res;
-	
+
 	/* Update data segment pointers for all libraries */
-	for (i=0; i<MAX_SHARED_LIBS; i++)
+	for (i = 0; i < MAX_SHARED_LIBS; i++)
 		if (libinfo.lib_list[i].loaded)
-			for (j=0; j<MAX_SHARED_LIBS; j++)
+			for (j = 0; j < MAX_SHARED_LIBS; j++)
 				(-(j+1))[(unsigned long *)(libinfo.lib_list[i].start_data)] =
-					(libinfo.lib_list[j].loaded)?
-						libinfo.lib_list[j].start_data:UNLOADED_LIB;
+					(libinfo.lib_list[j].loaded) ?
+						libinfo.lib_list[j].start_data : UNLOADED_LIB;
 
 	install_exec_creds(bprm);
 
 	set_binfmt(&flat_format);
 
 	p = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
-	DBG_FLT("p=%x\n", (int)p);
+	DBG_FLT("p=%lx\n", p);
 
 	/* copy the arg pages onto the stack, this could be more efficient :-) */
 	for (i = TOP_OF_ARGS - 1; i >= bprm->p; i--)
-		* (char *) --p =
+		*(char *) --p =
 			((char *) page_address(bprm->page[i/PAGE_SIZE]))[i % PAGE_SIZE];
 
 	sp = (unsigned long *) create_flat_tables(p, bprm);
-	
+
 	/* Fake some return addresses to ensure the call chain will
 	 * initialise library in order for us.  We are required to call
 	 * lib 1 first, then 2, ... and finally the main program (id 0).
@@ -915,7 +906,7 @@ static int load_flat_binary(struct linux_binprm * bprm)
 	start_addr = libinfo.lib_list[0].entry;
 
 #ifdef CONFIG_BINFMT_SHARED_FLAT
-	for (i = MAX_SHARED_LIBS-1; i>0; i--) {
+	for (i = MAX_SHARED_LIBS-1; i > 0; i--) {
 		if (libinfo.lib_list[i].loaded) {
 			/* Push previos first to call address */
 			--sp;	put_user(start_addr, sp);
@@ -923,16 +914,16 @@ static int load_flat_binary(struct linux_binprm * bprm)
 		}
 	}
 #endif
-	
+
 	/* Stash our initial stack pointer into the mm structure */
-	current->mm->start_stack = (unsigned long )sp;
+	current->mm->start_stack = (unsigned long)sp;
 
 #ifdef FLAT_PLAT_INIT
 	FLAT_PLAT_INIT(regs);
 #endif
-	DBG_FLT("start_thread(regs=0x%x, entry=0x%x, start_stack=0x%x)\n",
-		(int)regs, (int)start_addr, (int)current->mm->start_stack);
-	
+
+	DBG_FLT("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n",
+		regs, start_addr, current->mm->start_stack);
 	start_thread(regs, start_addr, current->mm->start_stack);
 
 	return 0;
@@ -945,9 +936,6 @@ static int __init init_flat_binfmt(void)
 	register_binfmt(&flat_format);
 	return 0;
 }
-
-/****************************************************************************/
-
 core_initcall(init_flat_binfmt);
 
 /****************************************************************************/
-- 
2.7.4

[PATCH v5 02/15] binfmt_flat: convert printk invocations to their modern form

[Nicolas Pitre]

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 fs/binfmt_flat.c | 118 ++++++++++++++++++++++++-------------------------------
 1 file changed, 51 insertions(+), 67 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 892dba62bf..c3ccdefdea 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -15,6 +15,8 @@
  *	JAN/99 -- coded full program relocation (gerg at snapgear.com)
  */
 
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -40,16 +42,6 @@
 
 /****************************************************************************/
 
-#if 0
-#define DEBUG 1
-#endif
-
-#ifdef DEBUG
-#define	DBG_FLT(a...)	printk(a)
-#else
-#define	DBG_FLT(a...)
-#endif
-
 /*
  * User data (data section and bss) needs to be aligned.
  * We pick 0x20 here because it is the max value elf2flt has always
@@ -102,8 +94,8 @@ static struct linux_binfmt flat_format = {
 
 static int flat_core_dump(struct coredump_params *cprm)
 {
-	printk("Process %s:%d received signr %d and should have core dumped\n",
-			current->comm, current->pid, cprm->siginfo->si_signo);
+	pr_warn("Process %s:%d received signr %d and should have core dumped\n",
+		current->comm, current->pid, cprm->siginfo->si_signo);
 	return 1;
 }
 
@@ -186,17 +178,17 @@ static int decompress_exec(
 	loff_t fpos;
 	int ret, retval;
 
-	DBG_FLT("decompress_exec(offset=%lx,buf=%p,len=%lx)\n", offset, dst, len);
+	pr_debug("decompress_exec(offset=%lx,buf=%p,len=%lx)\n", offset, dst, len);
 
 	memset(&strm, 0, sizeof(strm));
 	strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
 	if (strm.workspace == NULL) {
-		DBG_FLT("binfmt_flat: no memory for decompress workspace\n");
+		pr_debug("no memory for decompress workspace\n");
 		return -ENOMEM;
 	}
 	buf = kmalloc(LBUFSIZE, GFP_KERNEL);
 	if (buf == NULL) {
-		DBG_FLT("binfmt_flat: no memory for read buffer\n");
+		pr_debug("no memory for read buffer\n");
 		retval = -ENOMEM;
 		goto out_free;
 	}
@@ -214,25 +206,25 @@ static int decompress_exec(
 
 	/* Check minimum size -- gzip header */
 	if (ret < 10) {
-		DBG_FLT("binfmt_flat: file too small?\n");
+		pr_debug("file too small?\n");
 		goto out_free_buf;
 	}
 
 	/* Check gzip magic number */
 	if ((buf[0] != 037) || ((buf[1] != 0213) && (buf[1] != 0236))) {
-		DBG_FLT("binfmt_flat: unknown compression magic?\n");
+		pr_debug("unknown compression magic?\n");
 		goto out_free_buf;
 	}
 
 	/* Check gzip method */
 	if (buf[2] != 8) {
-		DBG_FLT("binfmt_flat: unknown compression method?\n");
+		pr_debug("unknown compression method?\n");
 		goto out_free_buf;
 	}
 	/* Check gzip flags */
 	if ((buf[3] & ENCRYPTED) || (buf[3] & CONTINUATION) ||
 	    (buf[3] & RESERVED)) {
-		DBG_FLT("binfmt_flat: unknown flags?\n");
+		pr_debug("unknown flags?\n");
 		goto out_free_buf;
 	}
 
@@ -240,7 +232,7 @@ static int decompress_exec(
 	if (buf[3] & EXTRA_FIELD) {
 		ret += 2 + buf[10] + (buf[11] << 8);
 		if (unlikely(ret >= LBUFSIZE)) {
-			DBG_FLT("binfmt_flat: buffer overflow (EXTRA)?\n");
+			pr_debug("buffer overflow (EXTRA)?\n");
 			goto out_free_buf;
 		}
 	}
@@ -248,7 +240,7 @@ static int decompress_exec(
 		while (ret < LBUFSIZE && buf[ret++] != 0)
 			;
 		if (unlikely(ret == LBUFSIZE)) {
-			DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
+			pr_debug("buffer overflow (ORIG_NAME)?\n");
 			goto out_free_buf;
 		}
 	}
@@ -256,7 +248,7 @@ static int decompress_exec(
 		while (ret < LBUFSIZE && buf[ret++] != 0)
 			;
 		if (unlikely(ret == LBUFSIZE)) {
-			DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");
+			pr_debug("buffer overflow (COMMENT)?\n");
 			goto out_free_buf;
 		}
 	}
@@ -269,7 +261,7 @@ static int decompress_exec(
 	strm.total_out = 0;
 
 	if (zlib_inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
-		DBG_FLT("binfmt_flat: zlib init failed?\n");
+		pr_debug("zlib init failed?\n");
 		goto out_free_buf;
 	}
 
@@ -286,7 +278,7 @@ static int decompress_exec(
 	}
 
 	if (ret < 0) {
-		DBG_FLT("binfmt_flat: decompression failed (%d), %s\n",
+		pr_debug("decompression failed (%d), %s\n",
 			ret, strm.msg);
 		goto out_zlib;
 	}
@@ -323,24 +315,23 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 		r &= 0x00ffffff;	/* Trim ID off here */
 	}
 	if (id >= MAX_SHARED_LIBS) {
-		printk("BINFMT_FLAT: reference 0x%lx to shared library %d",
-				r, id);
+		pr_err("reference 0x%lx to shared library %d", r, id);
 		goto failed;
 	}
 	if (curid != id) {
 		if (internalp) {
-			printk("BINFMT_FLAT: reloc address 0x%lx not in same module "
-					"(%d != %d)", r, curid, id);
+			pr_err("reloc address 0x%lx not in same module "
+			       "(%d != %d)", r, curid, id);
 			goto failed;
 		} else if (!p->lib_list[id].loaded &&
 			   load_flat_shared_library(id, p) < 0) {
-			printk("BINFMT_FLAT: failed to load library %d", id);
+			pr_err("failed to load library %d", id);
 			goto failed;
 		}
 		/* Check versioning information (i.e. time stamps) */
 		if (p->lib_list[id].build_date && p->lib_list[curid].build_date &&
 				p->lib_list[curid].build_date < p->lib_list[id].build_date) {
-			printk("BINFMT_FLAT: library %d is younger than %d", id, curid);
+			pr_err("library %d is younger than %d", id, curid);
 			goto failed;
 		}
 	}
@@ -354,7 +345,7 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 	text_len = p->lib_list[id].text_len;
 
 	if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
-		printk("BINFMT_FLAT: reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
+		pr_err("reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
 		       r, start_brk-start_data+text_len, text_len);
 		goto failed;
 	}
@@ -368,7 +359,7 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 	return addr;
 
 failed:
-	printk(", killing %s!\n", current->comm);
+	pr_cont(", killing %s!\n", current->comm);
 	send_sig(SIGSEGV, current, 0);
 
 	return RELOC_FAILED;
@@ -378,9 +369,7 @@ failed:
 
 static void old_reloc(unsigned long rl)
 {
-#ifdef DEBUG
 	static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
-#endif
 	flat_v2_reloc_t	r;
 	unsigned long *ptr;
 
@@ -391,11 +380,9 @@ static void old_reloc(unsigned long rl)
 	ptr = (unsigned long *) (current->mm->start_data + r.reloc.offset);
 #endif
 
-#ifdef DEBUG
-	printk("Relocation of variable at DATASEG+%x "
-		"(address %p, currently %lx) into segment %s\n",
-		r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);
-#endif
+	pr_debug("Relocation of variable at DATASEG+%x "
+		 "(address %p, currently %lx) into segment %s\n",
+		 r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);
 
 	switch (r.reloc.type) {
 	case OLD_FLAT_RELOC_TYPE_TEXT:
@@ -408,13 +395,11 @@ static void old_reloc(unsigned long rl)
 		*ptr += current->mm->end_data;
 		break;
 	default:
-		printk("BINFMT_FLAT: Unknown relocation type=%x\n", r.reloc.type);
+		pr_err("Unknown relocation type=%x\n", r.reloc.type);
 		break;
 	}
 
-#ifdef DEBUG
-	printk("Relocation became %lx\n", *ptr);
-#endif
+	pr_debug("Relocation became %lx\n", *ptr);
 }
 
 /****************************************************************************/
@@ -463,20 +448,19 @@ static int load_flat_file(struct linux_binprm *bprm,
 	}
 
 	if (flags & FLAT_FLAG_KTRACE)
-		printk("BINFMT_FLAT: Loading file: %s\n", bprm->filename);
+		pr_info("Loading file: %s\n", bprm->filename);
 
 	if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
-		printk("BINFMT_FLAT: bad flat file version 0x%x (supported "
-			"0x%lx and 0x%lx)\n",
-			rev, FLAT_VERSION, OLD_FLAT_VERSION);
+		pr_err("bad flat file version 0x%x (supported 0x%lx and 0x%lx)\n",
+		       rev, FLAT_VERSION, OLD_FLAT_VERSION);
 		ret = -ENOEXEC;
 		goto err;
 	}
 
 	/* Don't allow old format executables to use shared libraries */
 	if (rev == OLD_FLAT_VERSION && id != 0) {
-		printk("BINFMT_FLAT: shared libraries are not available before rev 0x%lx\n",
-				FLAT_VERSION);
+		pr_err("shared libraries are not available before rev 0x%lx\n",
+		       FLAT_VERSION);
 		ret = -ENOEXEC;
 		goto err;
 	}
@@ -490,7 +474,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 
 #ifndef CONFIG_BINFMT_ZFLAT
 	if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
-		printk("Support for ZFLAT executables is not enabled.\n");
+		pr_err("Support for ZFLAT executables is not enabled.\n");
 		ret = -ENOEXEC;
 		goto err;
 	}
@@ -536,7 +520,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 		 * this should give us a ROM ptr,  but if it doesn't we don't
 		 * really care
 		 */
-		DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
+		pr_debug("ROM mapping of file (we hope)\n");
 
 		textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
 				  MAP_PRIVATE|MAP_EXECUTABLE, 0);
@@ -544,7 +528,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			ret = textpos;
 			if (!textpos)
 				ret = -ENOMEM;
-			printk("Unable to mmap process text, errno %d\n", ret);
+			pr_err("Unable to mmap process text, errno %d\n", ret);
 			goto err;
 		}
 
@@ -557,7 +541,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			ret = realdatastart;
 			if (!realdatastart)
 				ret = -ENOMEM;
-			printk("Unable to allocate RAM for process data, "
+			pr_err("Unable to allocate RAM for process data, "
 			       "errno %d\n", ret);
 			vm_munmap(textpos, text_len);
 			goto err;
@@ -566,8 +550,8 @@ static int load_flat_file(struct linux_binprm *bprm,
 				MAX_SHARED_LIBS * sizeof(unsigned long),
 				FLAT_DATA_ALIGN);
 
-		DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%ld bytes): %lx\n",
-			data_len + bss_len + stack_len, datapos);
+		pr_debug("Allocated data+bss+stack (%ld bytes): %lx\n",
+			 data_len + bss_len + stack_len, datapos);
 
 		fpos = ntohl(hdr->data_start);
 #ifdef CONFIG_BINFMT_ZFLAT
@@ -582,7 +566,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 		}
 		if (IS_ERR_VALUE(result)) {
 			ret = result;
-			printk("Unable to read data+bss, errno %d\n", ret);
+			pr_err("Unable to read data+bss, errno %d\n", ret);
 			vm_munmap(textpos, text_len);
 			vm_munmap(realdatastart, len);
 			goto err;
@@ -603,7 +587,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			ret = textpos;
 			if (!textpos)
 				ret = -ENOMEM;
-			printk("Unable to allocate RAM for process text/data, "
+			pr_err("Unable to allocate RAM for process text/data, "
 			       "errno %d\n", ret);
 			goto err;
 		}
@@ -645,7 +629,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 		}
 		if (IS_ERR_VALUE(result)) {
 			ret = result;
-			printk("Unable to read code+data+bss, errno %d\n", ret);
+			pr_err("Unable to read code+data+bss, errno %d\n", ret);
 			vm_munmap(textpos, text_len + data_len + extra +
 				MAX_SHARED_LIBS * sizeof(unsigned long));
 			goto err;
@@ -675,12 +659,12 @@ static int load_flat_file(struct linux_binprm *bprm,
 	}
 
 	if (flags & FLAT_FLAG_KTRACE) {
-		printk("Mapping is %lx, Entry point is %x, data_start is %x\n",
-		       textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
-		printk("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
-		       id ? "Lib" : "Load", bprm->filename,
-		       start_code, end_code, datapos, datapos + data_len,
-		       datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
+		pr_info("Mapping is %lx, Entry point is %x, data_start is %x\n",
+			textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
+		pr_info("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
+			id ? "Lib" : "Load", bprm->filename,
+			start_code, end_code, datapos, datapos + data_len,
+			datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
 	}
 
 	/* Store the current module values into the global library structure */
@@ -890,7 +874,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	set_binfmt(&flat_format);
 
 	p = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
-	DBG_FLT("p=%lx\n", p);
+	pr_debug("p=%lx\n", p);
 
 	/* copy the arg pages onto the stack, this could be more efficient :-) */
 	for (i = TOP_OF_ARGS - 1; i >= bprm->p; i--)
@@ -922,8 +906,8 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	FLAT_PLAT_INIT(regs);
 #endif
 
-	DBG_FLT("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n",
-		regs, start_addr, current->mm->start_stack);
+	pr_debug("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n",
+		 regs, start_addr, current->mm->start_stack);
 	start_thread(regs, start_addr, current->mm->start_stack);
 
 	return 0;
-- 
2.7.4

[PATCH v5 03/15] binfmt_flat: prevent kernel dammage from corrupted executable headers

[Nicolas Pitre]

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 fs/binfmt_flat.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index c3ccdefdea..03301bad1f 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -466,6 +466,17 @@ static int load_flat_file(struct linux_binprm *bprm,
 	}
 
 	/*
+	 * Make sure the header params are sane.
+	 * 28 bits (256 MB) is way more than reasonable in this case.
+	 * If some top bits are set we have probable binary corruption.
+	*/
+	if ((text_len | data_len | bss_len | stack_len | full_data) >> 28) {
+		pr_err("bad header\n");
+		ret = -ENOEXEC;
+		goto err;
+	}
+
+	/*
 	 * fix up the flags for the older format,  there were all kinds
 	 * of endian hacks,  this only works for the simple cases
 	 */
-- 
2.7.4

[PATCH v5 04/15] elf_fdpic_transfer_args_to_stack(): make it generic

[Nicolas Pitre]

This copying of arguments and environment is common to both NOMMU
binary formats we support. Let's make the elf_fdpic version available
to the flat format as well.

While at it, improve the code a bit not to copy below the actual
data area.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_elf_fdpic.c   | 38 ++------------------------------------
 fs/exec.c               | 33 +++++++++++++++++++++++++++++++++
 include/linux/binfmts.h |  2 ++
 3 files changed, 37 insertions(+), 36 deletions(-)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 203589311b..464a972e88 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -67,8 +67,6 @@ static int create_elf_fdpic_tables(struct linux_binprm *, struct mm_struct *,
 				   struct elf_fdpic_params *);
 
 #ifndef CONFIG_MMU
-static int elf_fdpic_transfer_args_to_stack(struct linux_binprm *,
-					    unsigned long *);
 static int elf_fdpic_map_file_constdisp_on_uclinux(struct elf_fdpic_params *,
 						   struct file *,
 						   struct mm_struct *);
@@ -515,8 +513,9 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
 	sp = mm->start_stack;
 
 	/* stack the program arguments and environment */
-	if (elf_fdpic_transfer_args_to_stack(bprm, &sp) < 0)
+	if (transfer_args_to_stack(bprm, &sp) < 0)
 		return -EFAULT;
+	sp &= ~15;
 #endif
 
 	/*
@@ -711,39 +710,6 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
 
 /*****************************************************************************/
 /*
- * transfer the program arguments and environment from the holding pages onto
- * the stack
- */
-#ifndef CONFIG_MMU
-static int elf_fdpic_transfer_args_to_stack(struct linux_binprm *bprm,
-					    unsigned long *_sp)
-{
-	unsigned long index, stop, sp;
-	char *src;
-	int ret = 0;
-
-	stop = bprm->p >> PAGE_SHIFT;
-	sp = *_sp;
-
-	for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
-		src = kmap(bprm->page[index]);
-		sp -= PAGE_SIZE;
-		if (copy_to_user((void *) sp, src, PAGE_SIZE) != 0)
-			ret = -EFAULT;
-		kunmap(bprm->page[index]);
-		if (ret < 0)
-			goto out;
-	}
-
-	*_sp = (*_sp - (MAX_ARG_PAGES * PAGE_SIZE - bprm->p)) & ~15;
-
-out:
-	return ret;
-}
-#endif
-
-/*****************************************************************************/
-/*
  * load the appropriate binary image (executable or interpreter) into memory
  * - we assume no MMU is available
  * - if no other PIC bits are set in params->hdr->e_flags
diff --git a/fs/exec.c b/fs/exec.c
index 887c1c955d..ef0df2f092 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -762,6 +762,39 @@ out_unlock:
 }
 EXPORT_SYMBOL(setup_arg_pages);
 
+#else
+
+/*
+ * Transfer the program arguments and environment from the holding pages
+ * onto the stack. The provided stack pointer is adjusted accordingly.
+ */
+int transfer_args_to_stack(struct linux_binprm *bprm,
+			   unsigned long *sp_location)
+{
+	unsigned long index, stop, sp;
+	int ret = 0;
+
+	stop = bprm->p >> PAGE_SHIFT;
+	sp = *sp_location;
+
+	for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
+		unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
+		char *src = kmap(bprm->page[index]) + offset;
+		sp -= PAGE_SIZE - offset;
+		if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
+			ret = -EFAULT;
+		kunmap(bprm->page[index]);
+		if (ret)
+			goto out;
+	}
+
+	*sp_location = sp;
+
+out:
+	return ret;
+}
+EXPORT_SYMBOL(transfer_args_to_stack);
+
 #endif /* CONFIG_MMU */
 
 static struct file *do_open_execat(int fd, struct filename *name, int flags)
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 314b3caa70..1303b570b1 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -113,6 +113,8 @@ extern int suid_dumpable;
 extern int setup_arg_pages(struct linux_binprm * bprm,
 			   unsigned long stack_top,
 			   int executable_stack);
+extern int transfer_args_to_stack(struct linux_binprm *bprm,
+				  unsigned long *sp_location);
 extern int bprm_change_interp(char *interp, struct linux_binprm *bprm);
 extern int copy_strings_kernel(int argc, const char *const *argv,
 			       struct linux_binprm *bprm);
-- 
2.7.4

[PATCH v5 05/15] binfmt_flat: use generic transfer_args_to_stack()

[Nicolas Pitre]

This gets rid of the rather ugly, open coded and suboptimal copy code.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 03301bad1f..a002e1a3b9 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -846,10 +846,8 @@ static int load_flat_binary(struct linux_binprm *bprm)
 {
 	struct lib_info libinfo;
 	struct pt_regs *regs = current_pt_regs();
-	unsigned long p = bprm->p;
-	unsigned long stack_len;
+	unsigned long sp, stack_len;
 	unsigned long start_addr;
-	unsigned long *sp;
 	int res;
 	int i, j;
 
@@ -884,15 +882,15 @@ static int load_flat_binary(struct linux_binprm *bprm)
 
 	set_binfmt(&flat_format);
 
-	p = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
-	pr_debug("p=%lx\n", p);
+	sp = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
+	pr_debug("sp=%lx\n", sp);
 
-	/* copy the arg pages onto the stack, this could be more efficient :-) */
-	for (i = TOP_OF_ARGS - 1; i >= bprm->p; i--)
-		*(char *) --p =
-			((char *) page_address(bprm->page[i/PAGE_SIZE]))[i % PAGE_SIZE];
+	/* copy the arg pages onto the stack */
+	res = transfer_args_to_stack(bprm, &sp);
+	if (res)
+		return res;
 
-	sp = (unsigned long *) create_flat_tables(p, bprm);
+	sp = create_flat_tables(sp, bprm);
 
 	/* Fake some return addresses to ensure the call chain will
 	 * initialise library in order for us.  We are required to call
@@ -904,14 +902,14 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	for (i = MAX_SHARED_LIBS-1; i > 0; i--) {
 		if (libinfo.lib_list[i].loaded) {
 			/* Push previos first to call address */
-			--sp;	put_user(start_addr, sp);
+			--sp;	put_user(start_addr, (unsigned long *)sp);
 			start_addr = libinfo.lib_list[i].entry;
 		}
 	}
 #endif
 
 	/* Stash our initial stack pointer into the mm structure */
-	current->mm->start_stack = (unsigned long)sp;
+	current->mm->start_stack = sp;
 
 #ifdef FLAT_PLAT_INIT
 	FLAT_PLAT_INIT(regs);
-- 
2.7.4

[PATCH v5 06/15] binfmt_flat: clean up create_flat_tables() and stack accesses

[Nicolas Pitre]

In addition to better code clarity, this brings proper usage of
user memory accessors everywhere the stack is touched. This is essential
for making this work on MMU systems.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 117 ++++++++++++++++++++++++++++++-------------------------
 1 file changed, 63 insertions(+), 54 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index a002e1a3b9..5dc7968a42 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -103,50 +103,58 @@ static int flat_core_dump(struct coredump_params *cprm)
 /*
  * create_flat_tables() parses the env- and arg-strings in new user
  * memory and creates the pointer tables from them, and puts their
- * addresses on the "stack", returning the new stack pointer value.
+ * addresses on the "stack", recording the new stack pointer value.
  */
 
-static unsigned long create_flat_tables(
-	unsigned long pp,
-	struct linux_binprm *bprm)
+static int create_flat_tables(struct linux_binprm *bprm, unsigned long arg_start)
 {
-	unsigned long *argv, *envp;
-	unsigned long *sp;
-	char *p = (char *)pp;
-	int argc = bprm->argc;
-	int envc = bprm->envc;
-	char uninitialized_var(dummy);
-
-	sp = (unsigned long *)p;
-	sp -= (envc + argc + 2) + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
-	sp = (unsigned long *) ((unsigned long)sp & -FLAT_STACK_ALIGN);
-	argv = sp + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
-	envp = argv + (argc + 1);
+	char __user *p;
+	unsigned long __user *sp;
+	long i, len;
 
+	p = (char __user *)arg_start;
+	sp = (unsigned long __user *)current->mm->start_stack;
+
+	sp -= bprm->envc + 1;
+	sp -= bprm->argc + 1;
+	sp -= flat_argvp_envp_on_stack() ? 2 : 0;
+	sp -= 1;  /* &argc */
+
+	current->mm->start_stack = (unsigned long)sp & -FLAT_STACK_ALIGN;
+	sp = (unsigned long __user *)current->mm->start_stack;
+
+	__put_user(bprm->argc, sp++);
 	if (flat_argvp_envp_on_stack()) {
-		put_user((unsigned long) envp, sp + 2);
-		put_user((unsigned long) argv, sp + 1);
-	}
-
-	put_user(argc, sp);
-	current->mm->arg_start = (unsigned long) p;
-	while (argc-- > 0) {
-		put_user((unsigned long) p, argv++);
-		do {
-			get_user(dummy, p); p++;
-		} while (dummy);
-	}
-	put_user((unsigned long) NULL, argv);
-	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
-	while (envc-- > 0) {
-		put_user((unsigned long)p, envp); envp++;
-		do {
-			get_user(dummy, p); p++;
-		} while (dummy);
-	}
-	put_user((unsigned long) NULL, envp);
-	current->mm->env_end = (unsigned long) p;
-	return (unsigned long)sp;
+		unsigned long argv, envp;
+		argv = (unsigned long)(sp + 2);
+		envp = (unsigned long)(sp + 2 + bprm->argc + 1);
+		__put_user(argv, sp++);
+		__put_user(envp, sp++);
+	}
+
+	current->mm->arg_start = (unsigned long)p;
+	for (i = bprm->argc; i > 0; i--) {
+		__put_user((unsigned long)p, sp++);
+		len = strnlen_user(p, MAX_ARG_STRLEN);
+		if (!len || len > MAX_ARG_STRLEN)
+			return -EINVAL;
+		p += len;
+	}
+	__put_user(0, sp++);
+	current->mm->arg_end = (unsigned long)p;
+
+	current->mm->env_start = (unsigned long) p;
+	for (i = bprm->envc; i > 0; i--) {
+		__put_user((unsigned long)p, sp++);
+		len = strnlen_user(p, MAX_ARG_STRLEN);
+		if (!len || len > MAX_ARG_STRLEN)
+			return -EINVAL;
+		p += len;
+	}
+	__put_user(0, sp++);
+	current->mm->env_end = (unsigned long)p;
+
+	return 0;
 }
 
 /****************************************************************************/
@@ -846,7 +854,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
 {
 	struct lib_info libinfo;
 	struct pt_regs *regs = current_pt_regs();
-	unsigned long sp, stack_len;
+	unsigned long stack_len;
 	unsigned long start_addr;
 	int res;
 	int i, j;
@@ -860,11 +868,10 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	 * pedantic and include space for the argv/envp array as it may have
 	 * a lot of entries.
 	 */
-#define TOP_OF_ARGS (PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *))
-	stack_len = TOP_OF_ARGS - bprm->p;             /* the strings */
-	stack_len += (bprm->argc + 1) * sizeof(char *); /* the argv array */
-	stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
-	stack_len += FLAT_STACK_ALIGN - 1;  /* reserve for upcoming alignment */
+	stack_len = PAGE_SIZE * MAX_ARG_PAGES - bprm->p;  /* the strings */
+	stack_len += (bprm->argc + 1) * sizeof(char *);   /* the argv array */
+	stack_len += (bprm->envc + 1) * sizeof(char *);   /* the envp array */
+	stack_len = ALIGN(stack_len, FLAT_STACK_ALIGN);
 
 	res = load_flat_file(bprm, &libinfo, 0, &stack_len);
 	if (res < 0)
@@ -882,16 +889,18 @@ static int load_flat_binary(struct linux_binprm *bprm)
 
 	set_binfmt(&flat_format);
 
-	sp = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
-	pr_debug("sp=%lx\n", sp);
+	/* Stash our initial stack pointer into the mm structure */
+	current->mm->start_stack =
+		((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
+	pr_debug("sp=%lx\n", current->mm->start_stack);
 
 	/* copy the arg pages onto the stack */
-	res = transfer_args_to_stack(bprm, &sp);
+	res = transfer_args_to_stack(bprm, &current->mm->start_stack);
+	if (!res)
+		res = create_flat_tables(bprm, current->mm->start_stack);
 	if (res)
 		return res;
 
-	sp = create_flat_tables(sp, bprm);
-
 	/* Fake some return addresses to ensure the call chain will
 	 * initialise library in order for us.  We are required to call
 	 * lib 1 first, then 2, ... and finally the main program (id 0).
@@ -902,15 +911,15 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	for (i = MAX_SHARED_LIBS-1; i > 0; i--) {
 		if (libinfo.lib_list[i].loaded) {
 			/* Push previos first to call address */
-			--sp;	put_user(start_addr, (unsigned long *)sp);
+			unsigned long __user *sp;
+			current->mm->start_stack -= sizeof(unsigned long);
+			sp = (unsigned long __user *)current->mm->start_stack;
+			__put_user(start_addr, sp);
 			start_addr = libinfo.lib_list[i].entry;
 		}
 	}
 #endif
 
-	/* Stash our initial stack pointer into the mm structure */
-	current->mm->start_stack = sp;
-
 #ifdef FLAT_PLAT_INIT
 	FLAT_PLAT_INIT(regs);
 #endif
-- 
2.7.4

[PATCH v5 07/15] binfmt_flat: use proper user space accessors with relocs processing code

[Nicolas Pitre]

Relocs are fixed up in place in user space memory.  The appropriate
accessors are required for this code to work with an active MMU.

The architecture specific handlers flat_get_addr_from_rp() and
flat_put_addr_at_rp() for ARM and M68K are adjusted with separate
patches. SuperH and Xtensa are left out as they doesn't implement
__get_user_unaligned() and __put_user_unaligned() yet. The other
architectures that use BFLT don't have any MMU.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 5dc7968a42..9deafb282d 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -419,7 +419,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 	unsigned long textpos, datapos, realdatastart;
 	unsigned long text_len, data_len, bss_len, stack_len, full_data, flags;
 	unsigned long len, memp, memp_size, extra, rlim;
-	unsigned long *reloc, *rp;
+	unsigned long __user *reloc, *rp;
 	struct inode *inode;
 	int i, rev, relocs;
 	loff_t fpos;
@@ -591,7 +591,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			goto err;
 		}
 
-		reloc = (unsigned long *)
+		reloc = (unsigned long __user *)
 			(datapos + (ntohl(hdr->reloc_start) - text_len));
 		memp = realdatastart;
 		memp_size = len;
@@ -616,7 +616,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 				MAX_SHARED_LIBS * sizeof(unsigned long),
 				FLAT_DATA_ALIGN);
 
-		reloc = (unsigned long *)
+		reloc = (unsigned long __user *)
 			(datapos + (ntohl(hdr->reloc_start) - text_len));
 		memp = textpos;
 		memp_size = len;
@@ -708,15 +708,20 @@ static int load_flat_file(struct linux_binprm *bprm,
 	 * image.
 	 */
 	if (flags & FLAT_FLAG_GOTPIC) {
-		for (rp = (unsigned long *)datapos; *rp != 0xffffffff; rp++) {
-			unsigned long addr;
-			if (*rp) {
-				addr = calc_reloc(*rp, libinfo, id, 0);
+		for (rp = (unsigned long __user *)datapos; ; rp++) {
+			unsigned long addr, rp_val;
+			if (get_user(rp_val, rp))
+				return -EFAULT;
+			if (rp_val == 0xffffffff)
+				break;
+			if (rp_val) {
+				addr = calc_reloc(rp_val, libinfo, id, 0);
 				if (addr == RELOC_FAILED) {
 					ret = -ENOEXEC;
 					goto err;
 				}
-				*rp = addr;
+				if (put_user(addr, rp))
+					return -EFAULT;
 			}
 		}
 	}
@@ -733,7 +738,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 	 * __start to address 4 so that is okay).
 	 */
 	if (rev > OLD_FLAT_VERSION) {
-		unsigned long persistent = 0;
+		unsigned long __maybe_unused persistent = 0;
 		for (i = 0; i < relocs; i++) {
 			unsigned long addr, relval;
 
@@ -742,12 +747,14 @@ static int load_flat_file(struct linux_binprm *bprm,
 			 * relocated (of course, the address has to be
 			 * relocated first).
 			 */
-			relval = ntohl(reloc[i]);
+			if (get_user(relval, reloc + i))
+				return -EFAULT;
+			relval = ntohl(relval);
 			if (flat_set_persistent(relval, &persistent))
 				continue;
 			addr = flat_get_relocate_addr(relval);
-			rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
-			if (rp == (unsigned long *)RELOC_FAILED) {
+			rp = (unsigned long __user *)calc_reloc(addr, libinfo, id, 1);
+			if (rp == (unsigned long __user *)RELOC_FAILED) {
 				ret = -ENOEXEC;
 				goto err;
 			}
-- 
2.7.4

[PATCH v5 08/15] binfmt_flat: use proper user space accessors with old relocs code

[Nicolas Pitre]

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 9deafb282d..63756ca6a7 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -379,35 +379,38 @@ static void old_reloc(unsigned long rl)
 {
 	static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
 	flat_v2_reloc_t	r;
-	unsigned long *ptr;
+	unsigned long __user *ptr;
+	unsigned long val;
 
 	r.value = rl;
 #if defined(CONFIG_COLDFIRE)
-	ptr = (unsigned long *) (current->mm->start_code + r.reloc.offset);
+	ptr = (unsigned long __user *)(current->mm->start_code + r.reloc.offset);
 #else
-	ptr = (unsigned long *) (current->mm->start_data + r.reloc.offset);
+	ptr = (unsigned long __user *)(current->mm->start_data + r.reloc.offset);
 #endif
+	__get_user(val, ptr);
 
 	pr_debug("Relocation of variable at DATASEG+%x "
 		 "(address %p, currently %lx) into segment %s\n",
-		 r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);
+		 r.reloc.offset, ptr, val, segment[r.reloc.type]);
 
 	switch (r.reloc.type) {
 	case OLD_FLAT_RELOC_TYPE_TEXT:
-		*ptr += current->mm->start_code;
+		val += current->mm->start_code;
 		break;
 	case OLD_FLAT_RELOC_TYPE_DATA:
-		*ptr += current->mm->start_data;
+		val += current->mm->start_data;
 		break;
 	case OLD_FLAT_RELOC_TYPE_BSS:
-		*ptr += current->mm->end_data;
+		val += current->mm->end_data;
 		break;
 	default:
 		pr_err("Unknown relocation type=%x\n", r.reloc.type);
 		break;
 	}
+	__put_user(val, ptr);
 
-	pr_debug("Relocation became %lx\n", *ptr);
+	pr_debug("Relocation became %lx\n", val);
 }
 
 /****************************************************************************/
@@ -780,8 +783,13 @@ static int load_flat_file(struct linux_binprm *bprm,
 			}
 		}
 	} else {
-		for (i = 0; i < relocs; i++)
-			old_reloc(ntohl(reloc[i]));
+		for (i = 0; i < relocs; i++) {
+			unsigned long relval;
+			if (get_user(relval, reloc + i))
+				return -EFAULT;
+			relval = ntohl(relval);
+			old_reloc(relval);
+		}
 	}
 
 	flush_icache_range(start_code, end_code);
-- 
2.7.4

[PATCH v5 09/15] binfmt_flat: use clear_user() rather than memset() to clear .bss

[Nicolas Pitre]

This is needed on systems with a MMU.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 63756ca6a7..92c1530a2c 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -795,10 +795,11 @@ static int load_flat_file(struct linux_binprm *bprm,
 	flush_icache_range(start_code, end_code);
 
 	/* zero the BSS,  BRK and stack areas */
-	memset((void *)(datapos + data_len), 0, bss_len +
-			(memp + memp_size - stack_len -		/* end brk */
-			libinfo->lib_list[id].start_brk) +	/* start brk */
-			stack_len);
+	if (clear_user((void __user *)(datapos + data_len), bss_len +
+		       (memp + memp_size - stack_len -		/* end brk */
+		       libinfo->lib_list[id].start_brk) +	/* start brk */
+		       stack_len))
+		return -EFAULT;
 
 	return 0;
 err:
-- 
2.7.4

[PATCH v5 10/15] binfmt_flat: update libraries' data segment pointer with userspace accessors

[Nicolas Pitre]

This is needed on systems with a MMU.  This also gets rid of the
strangest C code I've seen lateli i.e. an integer indexed with a
pointer value within square brackets. That really looked backwards.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 92c1530a2c..aa7971ce6a 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -894,12 +894,19 @@ static int load_flat_binary(struct linux_binprm *bprm)
 		return res;
 
 	/* Update data segment pointers for all libraries */
-	for (i = 0; i < MAX_SHARED_LIBS; i++)
-		if (libinfo.lib_list[i].loaded)
-			for (j = 0; j < MAX_SHARED_LIBS; j++)
-				(-(j+1))[(unsigned long *)(libinfo.lib_list[i].start_data)] =
-					(libinfo.lib_list[j].loaded) ?
-						libinfo.lib_list[j].start_data : UNLOADED_LIB;
+	for (i = 0; i < MAX_SHARED_LIBS; i++) {
+		if (!libinfo.lib_list[i].loaded)
+			continue;
+		for (j = 0; j < MAX_SHARED_LIBS; j++) {
+			unsigned long val = libinfo.lib_list[j].loaded ?
+				libinfo.lib_list[j].start_data : UNLOADED_LIB;
+			unsigned long __user *p = (unsigned long __user *)
+				libinfo.lib_list[i].start_data;
+			p -= j + 1;
+			if (put_user(val, p))
+				return -EFAULT;
+		}
+	}
 
 	install_exec_creds(bprm);
 
-- 
2.7.4

[PATCH v5 11/15] binfmt_flat: add MMU-specific support

[Nicolas Pitre]

Not much else to do at this point except for the different stack setups.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index aa7971ce6a..7b999aebad 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -537,7 +537,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 	 * case,  and then the fully copied to RAM case which lumps
 	 * it all together.
 	 */
-	if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
+	if (!IS_ENABLED(CONFIG_MMU) && !(flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP))) {
 		/*
 		 * this should give us a ROM ptr,  but if it doesn't we don't
 		 * really care
@@ -677,7 +677,9 @@ static int load_flat_file(struct linux_binprm *bprm,
 		 */
 		current->mm->start_brk = datapos + data_len + bss_len;
 		current->mm->brk = (current->mm->start_brk + 3) & ~3;
+#ifndef CONFIG_MMU
 		current->mm->context.end_brk = memp + memp_size - stack_len;
+#endif
 	}
 
 	if (flags & FLAT_FLAG_KTRACE) {
@@ -870,7 +872,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
 {
 	struct lib_info libinfo;
 	struct pt_regs *regs = current_pt_regs();
-	unsigned long stack_len;
+	unsigned long stack_len = 0;
 	unsigned long start_addr;
 	int res;
 	int i, j;
@@ -884,7 +886,9 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	 * pedantic and include space for the argv/envp array as it may have
 	 * a lot of entries.
 	 */
-	stack_len = PAGE_SIZE * MAX_ARG_PAGES - bprm->p;  /* the strings */
+#ifndef CONFIG_MMU
+	stack_len += PAGE_SIZE * MAX_ARG_PAGES - bprm->p; /* the strings */
+#endif
 	stack_len += (bprm->argc + 1) * sizeof(char *);   /* the argv array */
 	stack_len += (bprm->envc + 1) * sizeof(char *);   /* the envp array */
 	stack_len = ALIGN(stack_len, FLAT_STACK_ALIGN);
@@ -912,6 +916,11 @@ static int load_flat_binary(struct linux_binprm *bprm)
 
 	set_binfmt(&flat_format);
 
+#ifdef CONFIG_MMU
+	res = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
+	if (!res)
+		res = create_flat_tables(bprm, bprm->p);
+#else
 	/* Stash our initial stack pointer into the mm structure */
 	current->mm->start_stack =
 		((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
@@ -921,6 +930,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	res = transfer_args_to_stack(bprm, &current->mm->start_stack);
 	if (!res)
 		res = create_flat_tables(bprm, current->mm->start_stack);
+#endif
 	if (res)
 		return res;
 
-- 
2.7.4

[PATCH v5 12/15] binfmt_flat: allow compressed flat binary format to work on MMU systems

[Nicolas Pitre]

Let's take the simple and obvious approach by decompressing the binary
into a kernel buffer and then copying it to user space.  Those who are
looking for top performance on an MMU system are unlikely to choose this
executable format anyway.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 7b999aebad..98cfefadb6 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -34,6 +34,7 @@
 #include <linux/init.h>
 #include <linux/flat.h>
 #include <linux/uaccess.h>
+#include <linux/vmalloc.h>
 
 #include <asm/byteorder.h>
 #include <asm/unaligned.h>
@@ -628,6 +629,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 		 * load it all in and treat it like a RAM load from now on
 		 */
 		if (flags & FLAT_FLAG_GZIP) {
+#ifndef CONFIG_MMU
 			result = decompress_exec(bprm, sizeof(struct flat_hdr),
 					 (((char *)textpos) + sizeof(struct flat_hdr)),
 					 (text_len + full_data
@@ -635,13 +637,51 @@ static int load_flat_file(struct linux_binprm *bprm,
 					 0);
 			memmove((void *) datapos, (void *) realdatastart,
 					full_data);
+#else
+			/*
+			 * This is used on MMU systems mainly for testing.
+			 * Let's use a kernel buffer to simplify things.
+			 */
+			long unz_text_len = text_len - sizeof(struct flat_hdr);
+			long unz_len = unz_text_len + full_data;
+			char *unz_data = vmalloc(unz_len);
+			if (!unz_data) {
+				result = -ENOMEM;
+			} else {
+				result = decompress_exec(bprm, sizeof(struct flat_hdr),
+							 unz_data, unz_len, 0);
+				if (result == 0 &&
+				    (copy_to_user((void __user *)textpos + sizeof(struct flat_hdr),
+						  unz_data, unz_text_len) ||
+				     copy_to_user((void __user *)datapos,
+						  unz_data + unz_text_len, full_data)))
+					result = -EFAULT;
+				vfree(unz_data);
+			}
+#endif
 		} else if (flags & FLAT_FLAG_GZDATA) {
 			result = read_code(bprm->file, textpos, 0, text_len);
-			if (!IS_ERR_VALUE(result))
+			if (!IS_ERR_VALUE(result)) {
+#ifndef CONFIG_MMU
 				result = decompress_exec(bprm, text_len, (char *) datapos,
 						 full_data, 0);
-		} else
+#else
+				char *unz_data = vmalloc(full_data);
+				if (!unz_data) {
+					result = -ENOMEM;
+				} else {
+					result = decompress_exec(bprm, text_len,
+						       unz_data, full_data, 0);
+					if (result == 0 &&
+					    copy_to_user((void __user *)datapos,
+							 unz_data, full_data))
+						result = -EFAULT;
+					vfree(unz_data);
+				}
 #endif
+			}
+		} else
+#endif /* CONFIG_BINFMT_ZFLAT */
 		{
 			result = read_code(bprm->file, textpos, 0, text_len);
 			if (!IS_ERR_VALUE(result))
-- 
2.7.4

[PATCH v5 12/15] binfmt_flat: allow compressed flat binary format to work on MMU systems

[Arnd Bergmann]

On Sunday, July 24, 2016 11:30:26 AM CEST Nicolas Pitre wrote:
> +#else
> +                       /*
> +                        * This is used on MMU systems mainly for testing.
> +                        * Let's use a kernel buffer to simplify things.
> +                        */
> +                       long unz_text_len = text_len - sizeof(struct flat_hdr);
> +                       long unz_len = unz_text_len + full_data;
> +                       char *unz_data = vmalloc(unz_len);
> +                       if (!unz_data) {
> +                               result = -ENOMEM;
> 

Is there a risk of a malicious user exhausting vmalloc space with a
binary that has forged headers? If there is, maybe put an upper bound on
the size of allocation.

More broadly speaking, are there any other attacks that may get enabled
through forged binaries? We've had a couple of vulnerabilities in
binfmt_elf over the years, and I wonder how dangerous it might be
if distros turn on binfmt_flat support by default.

	Arnd

[PATCH v5 12/15] binfmt_flat: allow compressed flat binary format to work on MMU systems

[Nicolas Pitre]

On Sun, 24 Jul 2016, Arnd Bergmann wrote:

> On Sunday, July 24, 2016 11:30:26 AM CEST Nicolas Pitre wrote:
> > +#else
> > +                       /*
> > +                        * This is used on MMU systems mainly for testing.
> > +                        * Let's use a kernel buffer to simplify things.
> > +                        */
> > +                       long unz_text_len = text_len - sizeof(struct flat_hdr);
> > +                       long unz_len = unz_text_len + full_data;
> > +                       char *unz_data = vmalloc(unz_len);
> > +                       if (!unz_data) {
> > +                               result = -ENOMEM;
> > 
> 
> Is there a risk of a malicious user exhausting vmalloc space with a
> binary that has forged headers? If there is, maybe put an upper bound on
> the size of allocation.

Patch #3 enforces a cap on all parameters to avoid overflows and 
unreasonable section sizes.

Then vmalloc space is used here only for decompressing the binary into, 
after which the whole thing is copied to user space and the vmalloc area 
is freed right away.

> More broadly speaking, are there any other attacks that may get enabled
> through forged binaries? We've had a couple of vulnerabilities in
> binfmt_elf over the years, and I wonder how dangerous it might be
> if distros turn on binfmt_flat support by default.

That was Alan's concern too which prompted patch #3. But with a clamp on 
all parameters, everything else is done via user accessors.  So an 
executable still can crap onto itself or generate a segfault but I doubt 
we really care at that point.


Nicolas

[PATCH v5 12/15] binfmt_flat: allow compressed flat binary format to work on MMU systems

[Arnd Bergmann]

On Sunday, July 24, 2016 4:25:16 PM CEST Nicolas Pitre wrote:
> On Sun, 24 Jul 2016, Arnd Bergmann wrote:
> 
> > On Sunday, July 24, 2016 11:30:26 AM CEST Nicolas Pitre wrote:
> > > +#else
> > > +                       /*
> > > +                        * This is used on MMU systems mainly for testing.
> > > +                        * Let's use a kernel buffer to simplify things.
> > > +                        */
> > > +                       long unz_text_len = text_len - sizeof(struct flat_hdr);
> > > +                       long unz_len = unz_text_len + full_data;
> > > +                       char *unz_data = vmalloc(unz_len);
> > > +                       if (!unz_data) {
> > > +                               result = -ENOMEM;
> > > 
> > 
> > Is there a risk of a malicious user exhausting vmalloc space with a
> > binary that has forged headers? If there is, maybe put an upper bound on
> > the size of allocation.
> 
> Patch #3 enforces a cap on all parameters to avoid overflows and 
> unreasonable section sizes.
> 
> Then vmalloc space is used here only for decompressing the binary into, 
> after which the whole thing is copied to user space and the vmalloc area 
> is freed right away.
> 
> > More broadly speaking, are there any other attacks that may get enabled
> > through forged binaries? We've had a couple of vulnerabilities in
> > binfmt_elf over the years, and I wonder how dangerous it might be
> > if distros turn on binfmt_flat support by default.
> 
> That was Alan's concern too which prompted patch #3. But with a clamp on 
> all parameters, everything else is done via user accessors.  So an 
> executable still can crap onto itself or generate a segfault but I doubt 
> we really care at that point.
> 

Ok, sounds good.

	Arnd

[PATCH v5 13/15] m68k: fix bFLT executable running on MMU enabled systems

[Nicolas Pitre]

From: Greg Ungerer <gerg@linux-m68k.org>

Even after recent changes to support running flat format executables on
MMU enabled systems (by nicolas.pitre at linaro.org) they still failed to
run on m68k/ColdFire MMU enabled systems. On trying to run a flat format
binary the application would immediately crash with a SIGSEGV.

Code to setup the D5 register with the base of the application data
region was only in the non-MMU code path, so it was not being set for
the MMU enabled case. Flat binaries on m68k/ColdFire use this to support
GOT/PIC flat built application code.

Fix this so that D5 is always setup when loading/running a bFLT executable
on m68k systems.

Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 arch/m68k/include/asm/flat.h      | 6 ++++++
 arch/m68k/include/asm/processor.h | 2 --
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/m68k/include/asm/flat.h b/arch/m68k/include/asm/flat.h
index f9454b89a5..f46c2f044f 100644
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -18,4 +18,10 @@ static inline int flat_set_persistent(unsigned long relval,
 	return 0;
 }
 
+#define FLAT_PLAT_INIT(regs) \
+	do { \
+		if (current->mm) \
+			(regs)->d5 = current->mm->start_data; \
+	} while (0)
+
 #endif /* __M68KNOMMU_FLAT_H__ */
diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index a6ce2ec8d6..46672d1f4d 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -131,8 +131,6 @@ extern int handle_kernel_fault(struct pt_regs *regs);
 do {                                                    \
 	(_regs)->pc = (_pc);                            \
 	setframeformat(_regs);                          \
-	if (current->mm)                                \
-		(_regs)->d5 = current->mm->start_data;  \
 	(_regs)->sr &= ~0x2000;                         \
 	wrusp(_usp);                                    \
 } while(0)
-- 
2.7.4

[PATCH v5 14/15] m68k: enable binfmt_flat on systems with an MMU

[Nicolas Pitre]

Now that the generic changes are in place, this can be enabled on m68k
with the use of proper user space accessors in the flat_get_addr_from_rp()
and flat_put_addr_at_rp() handlers as rp actually holds a user space
address.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 arch/m68k/include/asm/flat.h | 5 +++--
 fs/Kconfig.binfmt            | 3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/m68k/include/asm/flat.h b/arch/m68k/include/asm/flat.h
index f46c2f044f..a97c479b11 100644
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -8,8 +8,9 @@
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
-#define	flat_get_addr_from_rp(rp, relval, flags, p)	get_unaligned(rp)
-#define	flat_put_addr_at_rp(rp, val, relval)	put_unaligned(val,rp)
+#define	flat_get_addr_from_rp(rp, relval, flags, p) \
+	({ unsigned long __val; __get_user_unaligned(__val, rp); __val; })
+#define	flat_put_addr_at_rp(rp, val, relval)	__put_user_unaligned(val, rp)
 #define	flat_get_relocate_addr(rel)		(rel)
 
 static inline int flat_set_persistent(unsigned long relval,
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 72c03354c1..c7efddf6e0 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -89,7 +89,8 @@ config BINFMT_SCRIPT
 
 config BINFMT_FLAT
 	bool "Kernel support for flat binaries"
-	depends on !MMU && (!FRV || BROKEN)
+	depends on !MMU || M68K
+	depends on !FRV || BROKEN
 	help
 	  Support uClinux FLAT format binaries.
 
-- 
2.7.4

[PATCH v5 15/15] ARM: enable binfmt_flat on systems with an MMU

[Nicolas Pitre]

Now that the generic changes are in place, this can be enabled on ARM
with the use of proper user space accessors in the flat_get_addr_from_rp()
and flat_put_addr_at_rp() handlers as rp actually holds a user space
address.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 arch/arm/include/asm/flat.h | 5 +++--
 fs/Kconfig.binfmt           | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/flat.h b/arch/arm/include/asm/flat.h
index e847d23351..acf1d14b89 100644
--- a/arch/arm/include/asm/flat.h
+++ b/arch/arm/include/asm/flat.h
@@ -8,8 +8,9 @@
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
-#define	flat_get_addr_from_rp(rp, relval, flags, persistent) ((void)persistent,get_unaligned(rp))
-#define	flat_put_addr_at_rp(rp, val, relval)	put_unaligned(val,rp)
+#define	flat_get_addr_from_rp(rp, relval, flags, persistent) \
+	({ unsigned long __val; __get_user_unaligned(__val, rp); __val; })
+#define	flat_put_addr_at_rp(rp, val, relval)	__put_user_unaligned(val, rp)
 #define	flat_get_relocate_addr(rel)		(rel)
 #define	flat_set_persistent(relval, p)		0
 
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index c7efddf6e0..4c09d93d95 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -89,7 +89,7 @@ config BINFMT_SCRIPT
 
 config BINFMT_FLAT
 	bool "Kernel support for flat binaries"
-	depends on !MMU || M68K
+	depends on !MMU || ARM || M68K
 	depends on !FRV || BROKEN
 	help
 	  Support uClinux FLAT format binaries.
-- 
2.7.4

[PATCH v5 00/15] allow BFLT executables on systems with a MMU

[Greg Ungerer]

On 25/07/16 01:30, Nicolas Pitre wrote:
> This series provides the necessary changes to allow "flat" executable
> binaries meant for no-MMU systems to actually run on systems with a MMU.
> Also thrown in are various cleanups to binfmt_flat.c.
> 
> This can also be found in the following git repo:
> 
> 	git://git.linaro.org/people/nicolas.pitre/linux binfmt_flat_with_mmu

So everyone is in the loop - I have pulled this into my for-linus branch
at https://git.kernel.org/cgit/linux/kernel/git/gerg/m68knommu.git/ ,
excepting patch 15 (ARM specific changes).

My continued testing hasn't found any issues on m68k platforms.
I can completely boot up with a no-MMU user space and run on an
MMU enabled ColdFire platform).

I'll like to consider pushing this to Linus nearer the end of the
merge window if no-one has any objections.

Regards
Greg


> *Why?*
> 
> Because developing and testing natively on a large system with lots of
> RAM makes it so much more convenient to use all the existing profiling
> tools and debugging facilities that a kernel with lots of RAM can give.
> And incidentally, those systems with lots of RAM all have a MMU.
> 
> *Why not use elf_fdpic?*
> 
> The flat executable format is simple with very small footprint
> overhead, either in the executables themselves or kernel support.
> This makes the flat format more suitable than elf_fdpic for very small
> single user-app embedded systems.
> 
> And while elf_fdpic binaries can run on MMU systems, flat binaries still
> couldn't, which just felt wrong.
> 
> So here it is. The no-MMU support should remain unaffected, confirmed by
> Greg Ungerer. Tested with MMU on ARM and M68K.
> 
> Changes since v4:
> 
> - Isolated architecture specific changes in their own patches for easier
>   review through their own path to mainline.
> 
> - Added needed m68k register fixup from Greg Ungerer.
> 
> Changes since v3:
> 
> - Small cosmetic changes to pr_*().
> 
> - Addressed most important checkpatch complaints on the whole source file
>   and patches in this seris.
> 
> Changes since  v2:
> 
> - Added protection against a corrupted header that could have caused nasty
>   overflows etc. Suggested by Alan Cox.
> 
> - printk() modernization. Suggested by Greg Ungerer / Geert Uytterhoeven.
> 
> - Added Greg Ungerer's reviewed-by tag.
> 
> Changes since v1:
> 
> - Removed SuperH and Xtensa from the Kconfig rule as they fail to build
>   due to lack of get/put_unaligned_user().
> 
> - Clarified some commit logs a bit.
> 
> diffstat:
> 
>  arch/arm/include/asm/flat.h       |   5 +-
>  arch/m68k/include/asm/flat.h      |  11 +-
>  arch/m68k/include/asm/processor.h |   2 -
>  fs/Kconfig.binfmt                 |   3 +-
>  fs/binfmt_elf_fdpic.c             |  38 +--
>  fs/binfmt_flat.c                  | 525 ++++++++++++++++++--------------
>  fs/exec.c                         |  33 ++
>  include/linux/binfmts.h           |   2 +
>  8 files changed, 345 insertions(+), 274 deletions(-)
>