* [PATCH 1/3] ELF: delete "loc" variable
@ 2020-02-19 18:48 Alexey Dobriyan
2020-02-19 18:50 ` [PATCH 2/3] ELF: allocate less for static executable Alexey Dobriyan
0 siblings, 1 reply; 3+ messages in thread
From: Alexey Dobriyan @ 2020-02-19 18:48 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel
"loc" variable became just a wrapper for PT_INTERP ELF header after
main ELF header was moved to "bprm->buf". Delete it.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/binfmt_elf.c | 32 +++++++++++++++-----------------
1 file changed, 15 insertions(+), 17 deletions(-)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -698,15 +698,13 @@ static int load_elf_binary(struct linux_binprm *bprm)
unsigned long reloc_func_desc __maybe_unused = 0;
int executable_stack = EXSTACK_DEFAULT;
struct elfhdr *elf_ex = (struct elfhdr *)bprm->buf;
- struct {
- struct elfhdr interp_elf_ex;
- } *loc;
+ struct elfhdr *interp_elf_ex;
struct arch_elf_state arch_state = INIT_ARCH_ELF_STATE;
struct mm_struct *mm;
struct pt_regs *regs;
- loc = kmalloc(sizeof(*loc), GFP_KERNEL);
- if (!loc) {
+ interp_elf_ex = kmalloc(sizeof(*interp_elf_ex), GFP_KERNEL);
+ if (!interp_elf_ex) {
retval = -ENOMEM;
goto out_ret;
}
@@ -771,8 +769,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
would_dump(bprm, interpreter);
/* Get the exec headers */
- retval = elf_read(interpreter, &loc->interp_elf_ex,
- sizeof(loc->interp_elf_ex), 0);
+ retval = elf_read(interpreter, interp_elf_ex,
+ sizeof(*interp_elf_ex), 0);
if (retval < 0)
goto out_free_dentry;
@@ -806,25 +804,25 @@ static int load_elf_binary(struct linux_binprm *bprm)
if (interpreter) {
retval = -ELIBBAD;
/* Not an ELF interpreter */
- if (memcmp(loc->interp_elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
+ if (memcmp(interp_elf_ex->e_ident, ELFMAG, SELFMAG) != 0)
goto out_free_dentry;
/* Verify the interpreter has a valid arch */
- if (!elf_check_arch(&loc->interp_elf_ex) ||
- elf_check_fdpic(&loc->interp_elf_ex))
+ if (!elf_check_arch(interp_elf_ex) ||
+ elf_check_fdpic(interp_elf_ex))
goto out_free_dentry;
/* Load the interpreter program headers */
- interp_elf_phdata = load_elf_phdrs(&loc->interp_elf_ex,
+ interp_elf_phdata = load_elf_phdrs(interp_elf_ex,
interpreter);
if (!interp_elf_phdata)
goto out_free_dentry;
/* Pass PT_LOPROC..PT_HIPROC headers to arch code */
elf_ppnt = interp_elf_phdata;
- for (i = 0; i < loc->interp_elf_ex.e_phnum; i++, elf_ppnt++)
+ for (i = 0; i < interp_elf_ex->e_phnum; i++, elf_ppnt++)
switch (elf_ppnt->p_type) {
case PT_LOPROC ... PT_HIPROC:
- retval = arch_elf_pt_proc(&loc->interp_elf_ex,
+ retval = arch_elf_pt_proc(interp_elf_ex,
elf_ppnt, interpreter,
true, &arch_state);
if (retval)
@@ -839,7 +837,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
* the exec syscall.
*/
retval = arch_check_elf(elf_ex,
- !!interpreter, &loc->interp_elf_ex,
+ !!interpreter, interp_elf_ex,
&arch_state);
if (retval)
goto out_free_dentry;
@@ -1055,7 +1053,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
}
if (interpreter) {
- elf_entry = load_elf_interp(&loc->interp_elf_ex,
+ elf_entry = load_elf_interp(interp_elf_ex,
interpreter,
load_bias, interp_elf_phdata);
if (!IS_ERR((void *)elf_entry)) {
@@ -1064,7 +1062,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
* adjustment
*/
interp_load_addr = elf_entry;
- elf_entry += loc->interp_elf_ex.e_entry;
+ elf_entry += interp_elf_ex->e_entry;
}
if (BAD_ADDR(elf_entry)) {
retval = IS_ERR((void *)elf_entry) ?
@@ -1153,7 +1151,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
start_thread(regs, elf_entry, bprm->p);
retval = 0;
out:
- kfree(loc);
+ kfree(interp_elf_ex);
out_ret:
return retval;
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH 2/3] ELF: allocate less for static executable
2020-02-19 18:48 [PATCH 1/3] ELF: delete "loc" variable Alexey Dobriyan
@ 2020-02-19 18:50 ` Alexey Dobriyan
2020-02-19 18:53 ` [PATCH 3/3] ELF: don't free interpreter's ELF pheaders on common path Alexey Dobriyan
0 siblings, 1 reply; 3+ messages in thread
From: Alexey Dobriyan @ 2020-02-19 18:50 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel
PT_INTERP ELF header can be spared if executable is static.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/binfmt_elf.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -698,17 +698,11 @@ static int load_elf_binary(struct linux_binprm *bprm)
unsigned long reloc_func_desc __maybe_unused = 0;
int executable_stack = EXSTACK_DEFAULT;
struct elfhdr *elf_ex = (struct elfhdr *)bprm->buf;
- struct elfhdr *interp_elf_ex;
+ struct elfhdr *interp_elf_ex = NULL;
struct arch_elf_state arch_state = INIT_ARCH_ELF_STATE;
struct mm_struct *mm;
struct pt_regs *regs;
- interp_elf_ex = kmalloc(sizeof(*interp_elf_ex), GFP_KERNEL);
- if (!interp_elf_ex) {
- retval = -ENOMEM;
- goto out_ret;
- }
-
retval = -ENOEXEC;
/* First of all, some simple consistency checks */
if (memcmp(elf_ex->e_ident, ELFMAG, SELFMAG) != 0)
@@ -768,6 +762,12 @@ static int load_elf_binary(struct linux_binprm *bprm)
*/
would_dump(bprm, interpreter);
+ interp_elf_ex = kmalloc(sizeof(*interp_elf_ex), GFP_KERNEL);
+ if (!interp_elf_ex) {
+ retval = -ENOMEM;
+ goto out_free_ph;
+ }
+
/* Get the exec headers */
retval = elf_read(interpreter, interp_elf_ex,
sizeof(*interp_elf_ex), 0);
@@ -1073,6 +1073,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
allow_write_access(interpreter);
fput(interpreter);
+
+ kfree(interp_elf_ex);
} else {
elf_entry = e_entry;
if (BAD_ADDR(elf_entry)) {
@@ -1151,12 +1153,11 @@ static int load_elf_binary(struct linux_binprm *bprm)
start_thread(regs, elf_entry, bprm->p);
retval = 0;
out:
- kfree(interp_elf_ex);
-out_ret:
return retval;
/* error cleanup */
out_free_dentry:
+ kfree(interp_elf_ex);
kfree(interp_elf_phdata);
allow_write_access(interpreter);
if (interpreter)
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH 3/3] ELF: don't free interpreter's ELF pheaders on common path
2020-02-19 18:50 ` [PATCH 2/3] ELF: allocate less for static executable Alexey Dobriyan
@ 2020-02-19 18:53 ` Alexey Dobriyan
0 siblings, 0 replies; 3+ messages in thread
From: Alexey Dobriyan @ 2020-02-19 18:53 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel
Static executables don't need to free NULL pointer.
It doesn't matter really because static executable is not common
scenario but do it anyway out of pedantry.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/binfmt_elf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1075,6 +1075,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
fput(interpreter);
kfree(interp_elf_ex);
+ kfree(interp_elf_phdata);
} else {
elf_entry = e_entry;
if (BAD_ADDR(elf_entry)) {
@@ -1083,7 +1084,6 @@ static int load_elf_binary(struct linux_binprm *bprm)
}
}
- kfree(interp_elf_phdata);
kfree(elf_phdata);
set_binfmt(&elf_format);
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-02-19 18:53 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2020-02-19 18:48 [PATCH 1/3] ELF: delete "loc" variable Alexey Dobriyan
2020-02-19 18:50 ` [PATCH 2/3] ELF: allocate less for static executable Alexey Dobriyan
2020-02-19 18:53 ` [PATCH 3/3] ELF: don't free interpreter's ELF pheaders on common path Alexey Dobriyan
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