zram could kunmap_atomic a NULL pointer in a rare situation: a zram page become a full-zeroed page after a partial write io. The current code doesn't handle this case and kunmap_atomic a NULL porinter, which panic the kernel.
This patch fixes this issue. Signed-off-by: Weijie Yang <[email protected]> --- drivers/block/zram/zram_drv.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 2ad0b5b..3920ee4 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); -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
