From: Johannes Thumshirn johannes.thumshirn@wdc.com
commit da5e817d9d75422eaaa05490d0b9a5e328fc1a51 upstream.
Fstests runs on my VMs have show several kmemleak reports like the following.
unreferenced object 0xffff88811ae59080 (size 64): comm "xfs_io", pid 12124, jiffies 4294987392 (age 6.368s) hex dump (first 32 bytes): 00 c0 1c 00 00 00 00 00 ff cf 1c 00 00 00 00 00 ................ 90 97 e5 1a 81 88 ff ff 90 97 e5 1a 81 88 ff ff ................ backtrace: [<00000000ac0176d2>] ulist_add_merge+0x60/0x150 [btrfs] [<0000000076e9f312>] set_state_bits+0x86/0xc0 [btrfs] [<0000000014fe73d6>] set_extent_bit+0x270/0x690 [btrfs] [<000000004f675208>] set_record_extent_bits+0x19/0x20 [btrfs] [<00000000b96137b1>] qgroup_reserve_data+0x274/0x310 [btrfs] [<0000000057e9dcbb>] btrfs_check_data_free_space+0x5c/0xa0 [btrfs] [<0000000019c4511d>] btrfs_delalloc_reserve_space+0x1b/0xa0 [btrfs] [<000000006d37e007>] btrfs_dio_iomap_begin+0x415/0x970 [btrfs] [<00000000fb8a74b8>] iomap_iter+0x161/0x1e0 [<0000000071dff6ff>] __iomap_dio_rw+0x1df/0x700 [<000000002567ba53>] iomap_dio_rw+0x5/0x20 [<0000000072e555f8>] btrfs_file_write_iter+0x290/0x530 [btrfs] [<000000005eb3d845>] new_sync_write+0x106/0x180 [<000000003fb505bf>] vfs_write+0x24d/0x2f0 [<000000009bb57d37>] __x64_sys_pwrite64+0x69/0xa0 [<000000003eba3fdf>] do_syscall_64+0x43/0x90
In case brtfs_qgroup_reserve_data() or btrfs_delalloc_reserve_metadata() fail the allocated extent_changeset will not be freed.
So in btrfs_check_data_free_space() and btrfs_delalloc_reserve_space() free the allocated extent_changeset to get rid of the allocated memory.
The issue currently only happens in the direct IO write path, but only after 65b3c08606e5 ("btrfs: fix ENOSPC failure when attempting direct IO write into NOCOW range"), and also at defrag_one_locked_target(). Every other place is always calling extent_changeset_free() even if its call to btrfs_delalloc_reserve_space() or btrfs_check_data_free_space() has failed.
CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Denis Arefev arefev@swemel.ru --- Backport fix for CVE-2021-47508 Link: https://nvd.nist.gov/vuln/detail/cve-2021-47508 --- fs/btrfs/delalloc-space.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/delalloc-space.c b/fs/btrfs/delalloc-space.c index 45b2a5ecd63a..cd12226c3220 100644 --- a/fs/btrfs/delalloc-space.c +++ b/fs/btrfs/delalloc-space.c @@ -143,10 +143,13 @@ int btrfs_check_data_free_space(struct btrfs_inode *inode,
/* Use new btrfs_qgroup_reserve_data to reserve precious data space. */ ret = btrfs_qgroup_reserve_data(inode, reserved, start, len); - if (ret < 0) + if (ret < 0) { btrfs_free_reserved_data_space_noquota(fs_info, len); - else + extent_changeset_free(*reserved); + *reserved = NULL; + } else { ret = 0; + } return ret; }
@@ -446,8 +449,11 @@ int btrfs_delalloc_reserve_space(struct btrfs_inode *inode, if (ret < 0) return ret; ret = btrfs_delalloc_reserve_metadata(inode, len); - if (ret < 0) + if (ret < 0) { btrfs_free_reserved_data_space(inode, *reserved, start, len); + extent_changeset_free(*reserved); + *reserved = NULL; + } return ret; }