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| author | Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> | 2018-10-27 00:09:01 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-10-27 01:26:35 +0200 |
| commit | ff09d7ec9786be4ad7589aa987d7dc66e2dd9160 (patch) | |
| tree | 434364aec7ce46a9727f07011121bac423e9205e /mm/vmstat.c | |
| parent | mm: dax: add comment for PFN_SPECIAL (diff) | |
| download | linux-ff09d7ec9786be4ad7589aa987d7dc66e2dd9160.tar.xz linux-ff09d7ec9786be4ad7589aa987d7dc66e2dd9160.zip | |
mm/memory.c: recheck page table entry with page table lock held
We clear the pte temporarily during read/modify/write update of the pte.
If we take a page fault while the pte is cleared, the application can get
SIGBUS. One such case is with remap_pfn_range without a backing
vm_ops->fault callback. do_fault will return SIGBUS in that case.
cpu 0 cpu1
mprotect()
ptep_modify_prot_start()/pte cleared.
.
. page fault.
.
.
prep_modify_prot_commit()
Fix this by taking page table lock and rechecking for pte_none.
[aneesh.kumar@linux.ibm.com: fix crash observed with syzkaller run]
Link: http://lkml.kernel.org/r/87va6bwlfg.fsf@linux.ibm.com
Link: http://lkml.kernel.org/r/20180926031858.9692-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ido Schimmel <idosch@idosch.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmstat.c')
0 files changed, 0 insertions, 0 deletions