diff options
author | Nitin Gupta <ngupta@vflare.org> | 2013-01-02 08:53:41 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-13 19:40:02 -0800 |
commit | 397c60668aa5ae7130b5ad4e73870d7b8a787085 (patch) | |
tree | 3614efa94688c19233023c49d940fe0d3c061cf3 | |
parent | e16a922a27ec352537a8027cadc32dc156534ca5 (diff) |
staging: zram: fix invalid memory references during disk write
Fixes a bug introduced by commit c8f2f0db1 ("zram: Fix handling
of incompressible pages") which caused invalid memory references
during disk write. Invalid references could occur in two cases:
- Incoming data expands on compression: In this case, reference was
made to kunmap()'ed bio page.
- Partial (non PAGE_SIZE) write with incompressible data: In this
case, reference was made to a kfree()'ed buffer.
Fixes bug 50081:
https://bugzilla.kernel.org/show_bug.cgi?id=50081
Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Cc: stable <stable@vger.kernel.org>
Reported-by: Mihail Kasadjikov <hamer.mk@gmail.com>
Reported-by: Tomas M <tomas@slax.org>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/staging/zram/zram_drv.c | 39 |
1 files changed, 24 insertions, 15 deletions
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c index fb4a7c94aed3..f2a73bd739fb 100644 --- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -265,7 +265,7 @@ out_cleanup: static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, int offset) { - int ret; + int ret = 0; size_t clen; unsigned long handle; struct page *page; @@ -286,10 +286,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, goto out; } ret = zram_decompress_page(zram, uncmem, index); - if (ret) { - kfree(uncmem); + if (ret) goto out; - } } /* @@ -302,16 +300,18 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, user_mem = kmap_atomic(page); - if (is_partial_io(bvec)) + if (is_partial_io(bvec)) { memcpy(uncmem + offset, user_mem + bvec->bv_offset, bvec->bv_len); - else + kunmap_atomic(user_mem); + user_mem = NULL; + } else { uncmem = user_mem; + } if (page_zero_filled(uncmem)) { - kunmap_atomic(user_mem); - if (is_partial_io(bvec)) - kfree(uncmem); + if (!is_partial_io(bvec)) + kunmap_atomic(user_mem); zram_stat_inc(&zram->stats.pages_zero); zram_set_flag(zram, index, ZRAM_ZERO); ret = 0; @@ -321,9 +321,11 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen, zram->compress_workmem); - kunmap_atomic(user_mem); - if (is_partial_io(bvec)) - kfree(uncmem); + if (!is_partial_io(bvec)) { + kunmap_atomic(user_mem); + user_mem = NULL; + uncmem = NULL; + } if (unlikely(ret != LZO_E_OK)) { pr_err("Compression failed! err=%d\n", ret); @@ -332,8 +334,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, if (unlikely(clen > max_zpage_size)) { zram_stat_inc(&zram->stats.bad_compress); - src = uncmem; clen = PAGE_SIZE; + src = NULL; + if (is_partial_io(bvec)) + src = uncmem; } handle = zs_malloc(zram->mem_pool, clen); @@ -345,7 +349,11 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, } cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO); + if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) + src = kmap_atomic(page); memcpy(cmem, src, clen); + if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) + kunmap_atomic(src); zs_unmap_object(zram->mem_pool, handle); @@ -358,9 +366,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, if (clen <= PAGE_SIZE / 2) zram_stat_inc(&zram->stats.good_compress); - return 0; - out: + if (is_partial_io(bvec)) + kfree(uncmem); + if (ret) zram_stat64_inc(zram, &zram->stats.failed_writes); return ret; |