diff options
| author | Minchan Kim <minchan@kernel.org> | 2017-10-03 16:15:19 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-10-03 17:54:24 -0700 |
| commit | ae94264ed4b0cf7cd887947650db4c69acb62072 (patch) | |
| tree | 5e291f4bf79421a4a5b46122b31841844a67a98d | |
| parent | a872eb2131e91ce7c89a8888974a5e22a272b12f (diff) | |
| download | linux-ae94264ed4b0cf7cd887947650db4c69acb62072.tar.bz2 | |
zram: fix null dereference of handle
In testing I found handle passed to zs_map_object in __zram_bvec_read is
NULL so eh kernel goes oops in pin_object().
The reason is there is no routine to check the slot's freeing after
getting the slot's lock. This patch fixes it.
[minchan@kernel.org: v2]
Link: http://lkml.kernel.org/r/1505887347-10881-1-git-send-email-minchan@kernel.org
Link: http://lkml.kernel.org/r/1505788488-26723-1-git-send-email-minchan@kernel.org
Fixes: 1f7319c74275 ("zram: partial IO refactoring")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 36 |
1 files changed, 12 insertions, 24 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 2981c27d3aae..f149d3e61234 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -766,27 +766,6 @@ static void zram_slot_unlock(struct zram *zram, u32 index) bit_spin_unlock(ZRAM_ACCESS, &zram->table[index].value); } -static bool zram_same_page_read(struct zram *zram, u32 index, - struct page *page, - unsigned int offset, unsigned int len) -{ - zram_slot_lock(zram, index); - if (unlikely(!zram_get_handle(zram, index) || - zram_test_flag(zram, index, ZRAM_SAME))) { - void *mem; - - zram_slot_unlock(zram, index); - mem = kmap_atomic(page); - zram_fill_page(mem + offset, len, - zram_get_element(zram, index)); - kunmap_atomic(mem); - return true; - } - zram_slot_unlock(zram, index); - - return false; -} - static void zram_meta_free(struct zram *zram, u64 disksize) { size_t num_pages = disksize >> PAGE_SHIFT; @@ -884,11 +863,20 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, zram_slot_unlock(zram, index); } - if (zram_same_page_read(zram, index, page, 0, PAGE_SIZE)) - return 0; - zram_slot_lock(zram, index); handle = zram_get_handle(zram, index); + if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) { + unsigned long value; + void *mem; + + value = handle ? zram_get_element(zram, index) : 0; + mem = kmap_atomic(page); + zram_fill_page(mem, PAGE_SIZE, value); + kunmap_atomic(mem); + zram_slot_unlock(zram, index); + return 0; + } + size = zram_get_obj_size(zram, index); src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO); |