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authorMinchan Kim <minchan@kernel.org>2017-10-04 01:15:19 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2017-10-04 02:54:24 +0200
commitae94264ed4b0cf7cd887947650db4c69acb62072 (patch)
tree5e291f4bf79421a4a5b46122b31841844a67a98d /drivers/block
parentmm: fix RODATA_TEST failure "rodata_test: test data was not read only" (diff)
downloadlinux-ae94264ed4b0cf7cd887947650db4c69acb62072.tar.xz
linux-ae94264ed4b0cf7cd887947650db4c69acb62072.zip
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>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/zram/zram_drv.c36
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);