This is a note to let you know that I've just added the patch titled
zram: avoid kunmap_atomic() of a NULL pointer
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
zram-avoid-kunmap_atomic-of-a-null-pointer.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c406515239376fc93a30d5d03192182160cbd3fb Mon Sep 17 00:00:00 2001
From: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Date: Thu, 13 Nov 2014 15:19:05 -0800
Subject: zram: avoid kunmap_atomic() of a NULL pointer
From: Weijie Yang <weijie.yang@xxxxxxxxxxx>
commit c406515239376fc93a30d5d03192182160cbd3fb upstream.
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@xxxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Weijie Yang <weijie.yang.kh@xxxxxxxxx>
Acked-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -476,7 +476,8 @@ static int zram_bvec_write(struct zram *
}
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);
Patches currently in stable-queue which might be from weijie.yang@xxxxxxxxxxx are
queue-3.17/zram-avoid-kunmap_atomic-of-a-null-pointer.patch
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