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authorDave Hansen <dave@linux.vnet.ibm.com>2012-05-30 07:51:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-30 08:48:13 -0700
commit4523e1458566a0e8ecfaff90f380dd23acc44d27 (patch)
tree57e7423e1ec4e4f07ce8643d455297648bc31cb0 /mm
parentMerge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff)
downloadlinux-dev-4523e1458566a0e8ecfaff90f380dd23acc44d27.tar.xz
linux-dev-4523e1458566a0e8ecfaff90f380dd23acc44d27.zip
mm: fix vma_resv_map() NULL pointer
hugetlb_reserve_pages() can be used for either normal file-backed hugetlbfs mappings, or MAP_HUGETLB. In the MAP_HUGETLB, semi-anonymous mode, there is not a VMA around. The new call to resv_map_put() assumed that there was, and resulted in a NULL pointer dereference: BUG: unable to handle kernel NULL pointer dereference at 0000000000000030 IP: vma_resv_map+0x9/0x30 PGD 141453067 PUD 1421e1067 PMD 0 Oops: 0000 [#1] PREEMPT SMP ... Pid: 14006, comm: trinity-child6 Not tainted 3.4.0+ #36 RIP: vma_resv_map+0x9/0x30 ... Process trinity-child6 (pid: 14006, threadinfo ffff8801414e0000, task ffff8801414f26b0) Call Trace: resv_map_put+0xe/0x40 hugetlb_reserve_pages+0xa6/0x1d0 hugetlb_file_setup+0x102/0x2c0 newseg+0x115/0x360 ipcget+0x1ce/0x310 sys_shmget+0x5a/0x60 system_call_fastpath+0x16/0x1b This was reported by Dave Jones, but was reproducible with the libhugetlbfs test cases, so shame on me for not running them in the first place. With this, the oops is gone, and the output of libhugetlbfs's run_tests.py is identical to plain 3.4 again. [ Marked for stable, since this was introduced by commit c50ac050811d ("hugetlb: fix resv_map leak in error path") which was also marked for stable ] Reported-by: Dave Jones <davej@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <stable@vger.kernel.org> [2.6.32+] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/hugetlb.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 285a81e87ec8..e198831276a3 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3036,7 +3036,8 @@ int hugetlb_reserve_pages(struct inode *inode,
region_add(&inode->i_mapping->private_list, from, to);
return 0;
out_err:
- resv_map_put(vma);
+ if (vma)
+ resv_map_put(vma);
return ret;
}