The patch titled
Subject: zram: fix null dereference of handle
has been added to the -mm tree. Its filename is
zram-fix-null-dereference-of-handle.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-fix-null-dereference-of-handle.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-fix-null-dereference-of-handle.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: 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.
Link: http://lkml.kernel.org/r/1505788488-26723-1-git-send-email-minchan@xxxxxxxxxx
Fixes: 1f7319c74275 ("zram: partial IO refactoring")
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 34 +++++++++-----------------------
1 file changed, 10 insertions(+), 24 deletions(-)
diff -puN drivers/block/zram/zram_drv.c~zram-fix-null-dereference-of-handle drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-fix-null-dereference-of-handle
+++ a/drivers/block/zram/zram_drv.c
@@ -766,27 +766,6 @@ static void zram_slot_unlock(struct zram
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 +863,18 @@ static int __zram_bvec_read(struct zram
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 (unlikely(!handle || zram_test_flag(zram, index, ZRAM_SAME))) {
+ void *mem;
+
+ mem = kmap_atomic(page);
+ zram_fill_page(mem, PAGE_SIZE, zram_get_element(zram, index));
+ 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);
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
zram-fix-null-dereference-of-handle.patch
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