linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH -mm 1/3] ELF, coredump: allocate core ELF header on stack
Date: Sun, 22 Dec 2019 17:38:50 +0300	[thread overview]
Message-ID: <20191222143850.GA24341@avx2> (raw)

Comment says ELF header is "too large to be on stack".
64 bytes on 64-bit is not large by any means.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

 fs/binfmt_elf.c |   16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2186,7 +2186,7 @@ static int elf_core_dump(struct coredump_params *cprm)
 	int segs, i;
 	size_t vma_data_size = 0;
 	struct vm_area_struct *vma, *gate_vma;
-	struct elfhdr *elf = NULL;
+	struct elfhdr elf;
 	loff_t offset = 0, dataoff;
 	struct elf_note_info info = { };
 	struct elf_phdr *phdr4note = NULL;
@@ -2207,10 +2207,6 @@ static int elf_core_dump(struct coredump_params *cprm)
 	 * exists while dumping the mm->vm_next areas to the core file.
 	 */
   
-	/* alloc memory for large data structures: too large to be on stack */
-	elf = kmalloc(sizeof(*elf), GFP_KERNEL);
-	if (!elf)
-		goto out;
 	/*
 	 * The number of segs are recored into ELF header as 16bit value.
 	 * Please check DEFAULT_MAX_MAP_COUNT definition when you modify here.
@@ -2234,7 +2230,7 @@ static int elf_core_dump(struct coredump_params *cprm)
 	 * Collect all the non-memory information about the process for the
 	 * notes.  This also sets up the file header.
 	 */
-	if (!fill_note_info(elf, e_phnum, &info, cprm->siginfo, cprm->regs))
+	if (!fill_note_info(&elf, e_phnum, &info, cprm->siginfo, cprm->regs))
 		goto cleanup;
 
 	has_dumped = 1;
@@ -2242,7 +2238,7 @@ static int elf_core_dump(struct coredump_params *cprm)
 	fs = get_fs();
 	set_fs(KERNEL_DS);
 
-	offset += sizeof(*elf);				/* Elf header */
+	offset += sizeof(elf);				/* Elf header */
 	offset += segs * sizeof(struct elf_phdr);	/* Program headers */
 
 	/* Write notes phdr entry */
@@ -2285,12 +2281,12 @@ static int elf_core_dump(struct coredump_params *cprm)
 		shdr4extnum = kmalloc(sizeof(*shdr4extnum), GFP_KERNEL);
 		if (!shdr4extnum)
 			goto end_coredump;
-		fill_extnum_info(elf, shdr4extnum, e_shoff, segs);
+		fill_extnum_info(&elf, shdr4extnum, e_shoff, segs);
 	}
 
 	offset = dataoff;
 
-	if (!dump_emit(cprm, elf, sizeof(*elf)))
+	if (!dump_emit(cprm, &elf, sizeof(elf)))
 		goto end_coredump;
 
 	if (!dump_emit(cprm, phdr4note, sizeof(*phdr4note)))
@@ -2374,8 +2370,6 @@ static int elf_core_dump(struct coredump_params *cprm)
 	kfree(shdr4extnum);
 	kvfree(vma_filesz);
 	kfree(phdr4note);
-	kfree(elf);
-out:
 	return has_dumped;
 }
 

                 reply	other threads:[~2019-12-22 14:40 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191222143850.GA24341@avx2 \
    --to=adobriyan@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH -mm 1/3] ELF, coredump: allocate core ELF header on stack' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox