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 1/4] elf: don't be afraid of overflow
Date: Mon, 4 Feb 2019 23:27:15 +0300	[thread overview]
Message-ID: <20190204202715.GA27482@avx2> (raw)

Number of ELF program headers is 16-bit by spec, so total size
comfortably fits into "unsigned int".

Space savings: 7 bytes!

	add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-7 (-7)
	Function                                     old     new   delta
	load_elf_phdrs                               137     130      -7

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

 fs/binfmt_elf.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -418,8 +418,9 @@ static struct elf_phdr *load_elf_phdrs(struct elfhdr *elf_ex,
 				       struct file *elf_file)
 {
 	struct elf_phdr *elf_phdata = NULL;
-	int retval, size, err = -1;
+	int retval, err = -1;
 	loff_t pos = elf_ex->e_phoff;
+	unsigned int size;
 
 	/*
 	 * If the size of this structure has changed, then punt, since
@@ -429,13 +430,9 @@ static struct elf_phdr *load_elf_phdrs(struct elfhdr *elf_ex,
 		goto out;
 
 	/* Sanity check the number of program headers... */
-	if (elf_ex->e_phnum < 1 ||
-		elf_ex->e_phnum > 65536U / sizeof(struct elf_phdr))
-		goto out;
-
 	/* ...and their total size. */
 	size = sizeof(struct elf_phdr) * elf_ex->e_phnum;
-	if (size > ELF_MIN_ALIGN)
+	if (size == 0 || size > 65536 || size > ELF_MIN_ALIGN)
 		goto out;
 
 	elf_phdata = kmalloc(size, GFP_KERNEL);

             reply	other threads:[~2019-02-04 20:27 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-04 20:27 Alexey Dobriyan [this message]
2019-02-04 20:28 ` [PATCH 2/4] elf: use list_for_each_entry() Alexey Dobriyan
2019-02-04 20:28   ` [PATCH 3/4] elf: spread const a little Alexey Dobriyan
2019-02-04 20:33     ` [PATCH 4/4] elf: save allocation per exec Alexey Dobriyan
2019-02-12 15:49   ` [PATCH 2/4] elf: use list_for_each_entry() kbuild test robot
2019-02-12 16:21   ` kbuild test robot
2019-03-11 11:04 ` [PATCH 1/4] elf: don't be afraid of overflow Pavel Machek
2019-03-11 17:10   ` Alexey Dobriyan
2019-03-12  9:37     ` Pavel Machek

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=20190204202715.GA27482@avx2 \
    --to=adobriyan@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH 1/4] elf: don'\''t be afraid of overflow' \
    /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
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).