[ 3.8.y.z extended stable ] Patch "fs/binfmt_elf.c: prevent a coredump with a large vm_map_count from" has been added to staging queue
Kamal Mostafa
kamal at canonical.com
Wed Oct 9 20:51:23 UTC 2013
This is a note to let you know that I have just added a patch titled
fs/binfmt_elf.c: prevent a coredump with a large vm_map_count from
to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue
This patch is scheduled to be released in version 3.8.13.11.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
------
>From dedc20b7da535cab47a3bb059d301446d18d3dd9 Mon Sep 17 00:00:00 2001
From: Dan Aloni <alonid at stratoscale.com>
Date: Mon, 30 Sep 2013 13:45:02 -0700
Subject: fs/binfmt_elf.c: prevent a coredump with a large vm_map_count from
Oopsing
commit 72023656961b8c81a168a7a6762d589339d0d7ec upstream.
A high setting of max_map_count, and a process core-dumping with a large
enough vm_map_count could result in an NT_FILE note not being written,
and the kernel crashing immediately later because it has assumed
otherwise.
Reproduction of the oops-causing bug described here:
https://lkml.org/lkml/2013/8/30/50
Rge ussue originated in commit 2aa362c49c31 ("coredump: extend core dump
note section to contain file names of mapped file") from Oct 4, 2012.
This patch make that section optional in that case. fill_files_note()
should signify the error, and also let the info struct in
elf_core_dump() be zero-initialized so that we can check for the
optionally written note.
[akpm at linux-foundation.org: avoid abusing E2BIG, remove a couple of not-really-needed local variables]
[akpm at linux-foundation.org: fix sparse warning]
Signed-off-by: Dan Aloni <alonid at stratoscale.com>
Cc: Al Viro <viro at zeniv.linux.org.uk>
Cc: Denys Vlasenko <vda.linux at googlemail.com>
Reported-by: Martin MOKREJS <mmokrejs at gmail.com>
Tested-by: Martin MOKREJS <mmokrejs at gmail.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
fs/binfmt_elf.c | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 5843a47..0950e59 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1403,7 +1403,7 @@ static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
* long file_ofs
* followed by COUNT filenames in ASCII: "FILE1" NUL "FILE2" NUL...
*/
-static void fill_files_note(struct memelfnote *note)
+static int fill_files_note(struct memelfnote *note)
{
struct vm_area_struct *vma;
unsigned count, size, names_ofs, remaining, n;
@@ -1418,11 +1418,11 @@ static void fill_files_note(struct memelfnote *note)
names_ofs = (2 + 3 * count) * sizeof(data[0]);
alloc:
if (size >= MAX_FILE_NOTE_SIZE) /* paranoia check */
- goto err;
+ return -EINVAL;
size = round_up(size, PAGE_SIZE);
data = vmalloc(size);
if (!data)
- goto err;
+ return -ENOMEM;
start_end_ofs = data + 2;
name_base = name_curpos = ((char *)data) + names_ofs;
@@ -1475,7 +1475,7 @@ static void fill_files_note(struct memelfnote *note)
size = name_curpos - (char *)data;
fill_note(note, "CORE", NT_FILE, size, data);
- err: ;
+ return 0;
}
#ifdef CORE_DUMP_USE_REGSET
@@ -1676,8 +1676,8 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
fill_auxv_note(&info->auxv, current->mm);
info->size += notesize(&info->auxv);
- fill_files_note(&info->files);
- info->size += notesize(&info->files);
+ if (fill_files_note(&info->files) == 0)
+ info->size += notesize(&info->files);
return 1;
}
@@ -1709,7 +1709,8 @@ static int write_note_info(struct elf_note_info *info,
return 0;
if (first && !writenote(&info->auxv, file, foffset))
return 0;
- if (first && !writenote(&info->files, file, foffset))
+ if (first && info->files.data &&
+ !writenote(&info->files, file, foffset))
return 0;
for (i = 1; i < info->thread_notes; ++i)
@@ -1796,6 +1797,7 @@ static int elf_dump_thread_status(long signr, struct elf_thread_status *t)
struct elf_note_info {
struct memelfnote *notes;
+ struct memelfnote *notes_files;
struct elf_prstatus *prstatus; /* NT_PRSTATUS */
struct elf_prpsinfo *psinfo; /* NT_PRPSINFO */
struct list_head thread_list;
@@ -1886,9 +1888,12 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
fill_siginfo_note(info->notes + 2, &info->csigdata, siginfo);
fill_auxv_note(info->notes + 3, current->mm);
- fill_files_note(info->notes + 4);
+ info->numnote = 4;
- info->numnote = 5;
+ if (fill_files_note(info->notes + info->numnote) == 0) {
+ info->notes_files = info->notes + info->numnote;
+ info->numnote++;
+ }
/* Try to dump the FPU. */
info->prstatus->pr_fpvalid = elf_core_copy_task_fpregs(current, regs,
@@ -1950,8 +1955,9 @@ static void free_note_info(struct elf_note_info *info)
kfree(list_entry(tmp, struct elf_thread_status, list));
}
- /* Free data allocated by fill_files_note(): */
- vfree(info->notes[4].data);
+ /* Free data possibly allocated by fill_files_note(): */
+ if (info->notes_files)
+ vfree(info->notes_files->data);
kfree(info->prstatus);
kfree(info->psinfo);
@@ -2034,7 +2040,7 @@ static int elf_core_dump(struct coredump_params *cprm)
struct vm_area_struct *vma, *gate_vma;
struct elfhdr *elf = NULL;
loff_t offset = 0, dataoff, foffset;
- struct elf_note_info info;
+ struct elf_note_info info = { };
struct elf_phdr *phdr4note = NULL;
struct elf_shdr *shdr4extnum = NULL;
Elf_Half e_phnum;
--
1.8.1.2
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