From ae94264ed4b0cf7cd887947650db4c69acb62072 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Tue, 3 Oct 2017 16:15:19 -0700
Subject: [PATCH] zram: fix null dereference of handle
Git-commit: ae94264ed4b0cf7cd887947650db4c69acb62072
Patch-mainline: v4.14-rc4
References: bsc#1105355
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/block/zram/zram_drv.c | 36 ++++++++++++------------------------
1 file changed, 12 insertions(+), 24 deletions(-)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -432,27 +432,6 @@ 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 bool zram_same_page_write(struct zram *zram, u32 index,
struct page *page)
{
@@ -547,11 +526,20 @@ static int zram_decompress_page(struct z
unsigned int size;
void *src, *dst;
- 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);