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author | Greg Pearson <greg.pearson@hp.com> | 2014-02-10 14:25:36 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-02-10 16:01:40 -0800 |
commit | 38dfac843cb6d7be1874888839817404a15a6b3c (patch) | |
tree | 6dbd4b077fe973c6a54f549ce2e4ba4ab4b00635 /fs/proc/vmcore.c | |
parent | a3eb7fbb41eb8d6e22d491741b8c5d5aa6cb069a (diff) | |
download | linux-38dfac843cb6d7be1874888839817404a15a6b3c.tar.gz linux-38dfac843cb6d7be1874888839817404a15a6b3c.tar.bz2 linux-38dfac843cb6d7be1874888839817404a15a6b3c.zip |
vmcore: prevent PT_NOTE p_memsz overflow during header update
Currently, update_note_header_size_elf64() and
update_note_header_size_elf32() will add the size of a PT_NOTE entry to
real_sz even if that causes real_sz to exceeds max_sz. This patch
corrects the while loop logic in those routines to ensure that does not
happen and prints a warning if a PT_NOTE entry is dropped. If zero
PT_NOTE entries are found or this condition is encountered because the
only entry was dropped, a warning is printed and an error is returned.
One possible negative side effect of exceeding the max_sz limit is an
allocation failure in merge_note_headers_elf64() or
merge_note_headers_elf32() which would produce console output such as
the following while booting the crash kernel.
vmalloc: allocation failure: 14076997632 bytes
swapper/0: page allocation failure: order:0, mode:0x80d2
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-gbp1 #7
Call Trace:
dump_stack+0x19/0x1b
warn_alloc_failed+0xf0/0x160
__vmalloc_node_range+0x19e/0x250
vmalloc_user+0x4c/0x70
merge_note_headers_elf64.constprop.9+0x116/0x24a
vmcore_init+0x2d4/0x76c
do_one_initcall+0xe2/0x190
kernel_init_freeable+0x17c/0x207
kernel_init+0xe/0x180
ret_from_fork+0x7c/0xb0
Kdump: vmcore not initialized
kdump: dump target is /dev/sda4
kdump: saving to /sysroot//var/crash/127.0.0.1-2014.01.28-13:58:52/
kdump: saving vmcore-dmesg.txt
Cannot open /proc/vmcore: No such file or directory
kdump: saving vmcore-dmesg.txt failed
kdump: saving vmcore
kdump: saving vmcore failed
This type of failure has been seen on a four socket prototype system
with certain memory configurations. Most PT_NOTE sections have a single
entry similar to:
n_namesz = 0x5
n_descsz = 0x150
n_type = 0x1
Occasionally, a second entry is encountered with very large n_namesz and
n_descsz sizes:
n_namesz = 0x80000008
n_descsz = 0x510ae163
n_type = 0x80000008
Not yet sure of the source of these extra entries, they seem bogus, but
they shouldn't cause crash dump to fail.
Signed-off-by: Greg Pearson <greg.pearson@hp.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc/vmcore.c')
-rw-r--r-- | fs/proc/vmcore.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 2ca7ba047f04..88d4585b30f1 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -468,17 +468,24 @@ static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr) return rc; } nhdr_ptr = notes_section; - while (real_sz < max_sz) { - if (nhdr_ptr->n_namesz == 0) - break; + while (nhdr_ptr->n_namesz != 0) { sz = sizeof(Elf64_Nhdr) + ((nhdr_ptr->n_namesz + 3) & ~3) + ((nhdr_ptr->n_descsz + 3) & ~3); + if ((real_sz + sz) > max_sz) { + pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n", + nhdr_ptr->n_namesz, nhdr_ptr->n_descsz); + break; + } real_sz += sz; nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz); } kfree(notes_section); phdr_ptr->p_memsz = real_sz; + if (real_sz == 0) { + pr_warn("Warning: Zero PT_NOTE entries found\n"); + return -EINVAL; + } } return 0; @@ -648,17 +655,24 @@ static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr) return rc; } nhdr_ptr = notes_section; - while (real_sz < max_sz) { - if (nhdr_ptr->n_namesz == 0) - break; + while (nhdr_ptr->n_namesz != 0) { sz = sizeof(Elf32_Nhdr) + ((nhdr_ptr->n_namesz + 3) & ~3) + ((nhdr_ptr->n_descsz + 3) & ~3); + if ((real_sz + sz) > max_sz) { + pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n", + nhdr_ptr->n_namesz, nhdr_ptr->n_descsz); + break; + } real_sz += sz; nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz); } kfree(notes_section); phdr_ptr->p_memsz = real_sz; + if (real_sz == 0) { + pr_warn("Warning: Zero PT_NOTE entries found\n"); + return -EINVAL; + } } return 0; |