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staging: zram: fix random data read

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fd1a30de makes a bug that it uses (struct page *) as zsmalloc's handle
although it's a uncompressed page so that it can access random page,
return random data or even crashed by get_first_page in zs_map_object.

Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Minchan Kim 2012-06-08 15:39:26 +09:00 committed by Greg Kroah-Hartman
parent c234434835
commit 374a69191d
1 changed files with 8 additions and 7 deletions
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15
drivers/staging/zram/zram_drv.c
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@ -280,26 +280,27 @@ static int zram_read_before_write(struct zram *zram, char *mem, u32 index)
size_t clen = PAGE_SIZE;
struct zobj_header *zheader;
unsigned char *cmem;
unsigned long handle = zram->table[index].handle;
if (zram_test_flag(zram, index, ZRAM_ZERO) ||
!zram->table[index].handle) {
if (zram_test_flag(zram, index, ZRAM_ZERO) || !handle) {
memset(mem, 0, PAGE_SIZE);
return 0;
}
cmem = zs_map_object(zram->mem_pool, zram->table[index].handle);
/* Page is stored uncompressed since it's incompressible */
if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
memcpy(mem, cmem, PAGE_SIZE);
kunmap_atomic(cmem);
char *src = kmap_atomic((struct page *)handle);
memcpy(mem, src, PAGE_SIZE);
kunmap_atomic(src);
return 0;
}
cmem = zs_map_object(zram->mem_pool, handle);
ret = lzo1x_decompress_safe(cmem + sizeof(*zheader),
zram->table[index].size,
mem, &clen);
zs_unmap_object(zram->mem_pool, zram->table[index].handle);
zs_unmap_object(zram->mem_pool, handle);
/* Should NEVER happen. Return bio error if it does. */
if (unlikely(ret != LZO_E_OK)) {