Commit c4065152 authored Nov 13, 2014 by Weijie Yang Committed by Linus Torvalds Nov 13, 2014

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>

parent 2c54396e

drivers/block/zram/zram_drv.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -560,6 +560,7 @@ static int zram_bvec_write(struct zram zram, struct bio_vec bvec, u32 index,
		}

		if (page_zero_filled(uncmem)) {
		if (user_mem)
		kunmap_atomic(user_mem);
		/* Free memory associated with this sector now. */
		bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);