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authorWeijie Yang <weijie.yang@samsung.com>2014-11-13 15:19:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-11-13 16:17:05 -0800
commitc406515239376fc93a30d5d03192182160cbd3fb (patch)
tree41269ecf1d06e46fce5164d02b0b29ca78e8976e /drivers
parent2c54396e40c79876a7ddfd3231c81eedf639795b (diff)
zram: avoid kunmap_atomic() of a NULL pointer
zram could kunmap_atomic() a NULL pointer in a rare situation: a zram page becomes a full-zeroed page after a partial write io. The current code doesn't handle this case and performs kunmap_atomic() on a NULL pointer, which panics the kernel. This patch fixes this issue. Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Weijie Yang <weijie.yang.kh@gmail.com> Acked-by: Jerome Marchand <jmarchan@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/block/zram/zram_drv.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 2ad0b5bce44b..3920ee45aa59 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -560,7 +560,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
}
if (page_zero_filled(uncmem)) {
- kunmap_atomic(user_mem);
+ if (user_mem)
+ kunmap_atomic(user_mem);
/* Free memory associated with this sector now. */
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
zram_free_page(zram, index);

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