Fix CVE-2024-50278.
Ming-Hung Tsai (3): dm cache: fix out-of-bounds access to the dirty bitset when resizing dm cache: optimize dirty bit checking with find_next_bit when resizing dm cache: fix potential out-of-bounds access on the first resume
drivers/md/dm-cache-target.c | 27 +++++++++++---------------- 1 file changed, 11 insertions(+), 16 deletions(-)
From: Ming-Hung Tsai mtsai@redhat.com
stable inclusion from stable-v4.19.324 commit 4fa4feb873cea0e9d6ff883b37cca6f33169d8b4 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB5AV2 CVE: CVE-2024-50278
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
--------------------------------
commit 792227719725497ce10a8039803bec13f89f8910 upstream.
dm-cache checks the dirty bits of the cache blocks to be dropped when shrinking the fast device, but an index bug in bitset iteration causes out-of-bounds access.
Reproduce steps:
1. create a cache device of 1024 cache blocks (128 bytes dirty bitset)
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
2. shrink the fast device to 512 cache blocks, triggering out-of-bounds access to the dirty bitset (offset 0x80)
dmsetup suspend cache dmsetup reload cdata --table "0 65536 linear /dev/sdc 8192" dmsetup resume cdata dmsetup resume cache
KASAN reports:
BUG: KASAN: vmalloc-out-of-bounds in cache_preresume+0x269/0x7b0 Read of size 8 at addr ffffc900000f3080 by task dmsetup/131
(...snip...) The buggy address belongs to the virtual mapping at [ffffc900000f3000, ffffc900000f5000) created by: cache_ctr+0x176a/0x35f0
(...snip...) Memory state around the buggy address: ffffc900000f2f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900000f3000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc900000f3080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
^ ffffc900000f3100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900000f3180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
Fix by making the index post-incremented.
Signed-off-by: Ming-Hung Tsai mtsai@redhat.com Fixes: f494a9c6b1b6 ("dm cache: cache shrinking support") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka mpatocka@redhat.com Acked-by: Joe Thornber thornber@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Qixing zhengqixing@huawei.com --- drivers/md/dm-cache-target.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 2ddd575e97f7..9f58af2f0da3 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2997,13 +2997,13 @@ static bool can_resize(struct cache *cache, dm_cblock_t new_size) * We can't drop a dirty block when shrinking the cache. */ while (from_cblock(new_size) < from_cblock(cache->cache_size)) { - new_size = to_cblock(from_cblock(new_size) + 1); if (is_dirty(cache, new_size)) { DMERR("%s: unable to shrink cache; cache block %llu is dirty", cache_device_name(cache), (unsigned long long) from_cblock(new_size)); return false; } + new_size = to_cblock(from_cblock(new_size) + 1); }
return true;
From: Ming-Hung Tsai mtsai@redhat.com
stable inclusion from stable-v4.19.324 commit c90c5e02556d2781b6506ab4b8dd7613d9008bcd category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB5AV2 CVE: CVE-2024-50278
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit f484697e619a83ecc370443a34746379ad99d204 upstream.
When shrinking the fast device, dm-cache iteratively searches for a dirty bit among the cache blocks to be dropped, which is less efficient. Use find_next_bit instead, as it is twice as fast as the iterative approach with test_bit.
Signed-off-by: Ming-Hung Tsai mtsai@redhat.com Fixes: f494a9c6b1b6 ("dm cache: cache shrinking support") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka mpatocka@redhat.com Acked-by: Joe Thornber thornber@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Qixing zhengqixing@huawei.com --- drivers/md/dm-cache-target.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 9f58af2f0da3..4ceac733f541 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2996,14 +2996,14 @@ static bool can_resize(struct cache *cache, dm_cblock_t new_size) /* * We can't drop a dirty block when shrinking the cache. */ - while (from_cblock(new_size) < from_cblock(cache->cache_size)) { - if (is_dirty(cache, new_size)) { - DMERR("%s: unable to shrink cache; cache block %llu is dirty", - cache_device_name(cache), - (unsigned long long) from_cblock(new_size)); - return false; - } - new_size = to_cblock(from_cblock(new_size) + 1); + new_size = to_cblock(find_next_bit(cache->dirty_bitset, + from_cblock(cache->cache_size), + from_cblock(new_size))); + if (new_size != cache->cache_size) { + DMERR("%s: unable to shrink cache; cache block %llu is dirty", + cache_device_name(cache), + (unsigned long long) from_cblock(new_size)); + return false; }
return true;
From: Ming-Hung Tsai mtsai@redhat.com
stable inclusion from stable-v4.19.324 commit e492f71854ce03474d49e87fd98b8df1f7cd1d2d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB5AV2 CVE: CVE-2024-50278
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
--------------------------------
commit c0ade5d98979585d4f5a93e4514c2e9a65afa08d upstream.
Out-of-bounds access occurs if the fast device is expanded unexpectedly before the first-time resume of the cache table. This happens because expanding the fast device requires reloading the cache table for cache_create to allocate new in-core data structures that fit the new size, and the check in cache_preresume is not performed during the first resume, leading to the issue.
Reproduce steps:
1. prepare component devices:
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 65536 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct
2. load a cache table of 512 cache blocks, and deliberately expand the fast device before resuming the cache, making the in-core data structures inadequate.
dmsetup create cache --notable dmsetup reload cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" dmsetup reload cdata --table "0 131072 linear /dev/sdc 8192" dmsetup resume cdata dmsetup resume cache
3. suspend the cache to write out the in-core dirty bitset and hint array, leading to out-of-bounds access to the dirty bitset at offset 0x40:
dmsetup suspend cache
KASAN reports:
BUG: KASAN: vmalloc-out-of-bounds in is_dirty_callback+0x2b/0x80 Read of size 8 at addr ffffc90000085040 by task dmsetup/90
(...snip...) The buggy address belongs to the virtual mapping at [ffffc90000085000, ffffc90000087000) created by: cache_ctr+0x176a/0x35f0
(...snip...) Memory state around the buggy address: ffffc90000084f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90000084f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
ffffc90000085000: 00 00 00 00 00 00 00 00 f8 f8 f8 f8 f8 f8 f8 f8
^ ffffc90000085080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90000085100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
Fix by checking the size change on the first resume.
Signed-off-by: Ming-Hung Tsai mtsai@redhat.com Fixes: f494a9c6b1b6 ("dm cache: cache shrinking support") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka mpatocka@redhat.com Acked-by: Joe Thornber thornber@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Qixing zhengqixing@huawei.com --- drivers/md/dm-cache-target.c | 37 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 21 deletions(-)
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 4ceac733f541..67dba1a2c47e 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2986,24 +2986,24 @@ static dm_cblock_t get_cache_dev_size(struct cache *cache) static bool can_resize(struct cache *cache, dm_cblock_t new_size) { if (from_cblock(new_size) > from_cblock(cache->cache_size)) { - if (cache->sized) { - DMERR("%s: unable to extend cache due to missing cache table reload", - cache_device_name(cache)); - return false; - } + DMERR("%s: unable to extend cache due to missing cache table reload", + cache_device_name(cache)); + return false; }
/* * We can't drop a dirty block when shrinking the cache. */ - new_size = to_cblock(find_next_bit(cache->dirty_bitset, - from_cblock(cache->cache_size), - from_cblock(new_size))); - if (new_size != cache->cache_size) { - DMERR("%s: unable to shrink cache; cache block %llu is dirty", - cache_device_name(cache), - (unsigned long long) from_cblock(new_size)); - return false; + if (cache->loaded_mappings) { + new_size = to_cblock(find_next_bit(cache->dirty_bitset, + from_cblock(cache->cache_size), + from_cblock(new_size))); + if (new_size != cache->cache_size) { + DMERR("%s: unable to shrink cache; cache block %llu is dirty", + cache_device_name(cache), + (unsigned long long) from_cblock(new_size)); + return false; + } }
return true; @@ -3034,20 +3034,15 @@ static int cache_preresume(struct dm_target *ti) /* * Check to see if the cache has resized. */ - if (!cache->sized) { - r = resize_cache_dev(cache, csize); - if (r) - return r; - - cache->sized = true; - - } else if (csize != cache->cache_size) { + if (!cache->sized || csize != cache->cache_size) { if (!can_resize(cache, csize)) return -EINVAL;
r = resize_cache_dev(cache, csize); if (r) return r; + + cache->sized = true; }
if (!cache->loaded_mappings) {
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