In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
btrfs: balance: fix potential bg lookup failure in btrfs_may_alloc_data_chunk()<\/p>\n
[BUG]
\nRunning btrfs balance can trigger a null-ptr-deref before relocating a
\ndata chunk when metadata corruption leaves a chunk in the chunk tree
\nwithout a corresponding block group in the in-memory cache:<\/p>\n
KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]
\n RIP: 0010:btrfs_may_alloc_data_chunk+0x40\/0x1c0 fs\/btrfs\/volumes.c:3601
\n Call Trace:
\n __btrfs_balance fs\/btrfs\/volumes.c:4217 [inline]
\n btrfs_balance+0x2516\/0x42b0 fs\/btrfs\/volumes.c:4604
\n btrfs_ioctl_balance fs\/btrfs\/ioctl.c:3577 [inline]
\n btrfs_ioctl+0x25cf\/0x5b90 fs\/btrfs\/ioctl.c:5313
\n …<\/p>\n
[CAUSE]
\n__btrfs_balance() iterates the on-disk chunk tree and passes the chunk
\nlogical bytenr to btrfs_may_alloc_data_chunk() before relocating a data
\nchunk. That helper then queries the in-memory block group cache:<\/p>\n
cache = btrfs_lookup_block_group(fs_info, chunk_offset);
\n chunk_type = cache->flags; \/* cache may be NULL *\/<\/p>\n
A corrupt image can contain a chunk item whose matching block group
\nitem is missing, so no block group is ever inserted into the cache. In
\nthat case btrfs_lookup_block_group() returns NULL.<\/p>\n
The code only guards this with ASSERT(cache), which becomes a no-op when
\nCONFIG_BTRFS_ASSERT is disabled. The subsequent dereference of
\ncache->flags therefore crashes the kernel.<\/p>\n
[FIX]
\nAdd a NULL check after btrfs_lookup_block_group() in
\nbtrfs_may_alloc_data_chunk() and print and error message for clarity.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
btrfs: balance: fix potential bg lookup failure in btrfs_may_alloc_data_chunk()<\/p>\n
[BUG]
\nRunning btrfs balance can trigger a null-ptr<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-28663","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/28663","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28663"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28663"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28663"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}