CVE-2021-47508 (GCVE-0-2021-47508)
Vulnerability from cvelistv5
Published
2024-05-24 15:01
Modified
2026-05-11 13:56
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: free exchange changeset on failures 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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 364ecf3651e0862152c8b340d7cb3021dc0122c7
Version: 364ecf3651e0862152c8b340d7cb3021dc0122c7
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: free exchange changeset on failures\n\nFstests runs on my VMs have show several kmemleak reports like the following.\n\n  unreferenced object 0xffff88811ae59080 (size 64):\n    comm \"xfs_io\", pid 12124, jiffies 4294987392 (age 6.368s)\n    hex dump (first 32 bytes):\n      00 c0 1c 00 00 00 00 00 ff cf 1c 00 00 00 00 00  ................\n      90 97 e5 1a 81 88 ff ff 90 97 e5 1a 81 88 ff ff  ................\n    backtrace:\n      [\u003c00000000ac0176d2\u003e] ulist_add_merge+0x60/0x150 [btrfs]\n      [\u003c0000000076e9f312\u003e] set_state_bits+0x86/0xc0 [btrfs]\n      [\u003c0000000014fe73d6\u003e] set_extent_bit+0x270/0x690 [btrfs]\n      [\u003c000000004f675208\u003e] set_record_extent_bits+0x19/0x20 [btrfs]\n      [\u003c00000000b96137b1\u003e] qgroup_reserve_data+0x274/0x310 [btrfs]\n      [\u003c0000000057e9dcbb\u003e] btrfs_check_data_free_space+0x5c/0xa0 [btrfs]\n      [\u003c0000000019c4511d\u003e] btrfs_delalloc_reserve_space+0x1b/0xa0 [btrfs]\n      [\u003c000000006d37e007\u003e] btrfs_dio_iomap_begin+0x415/0x970 [btrfs]\n      [\u003c00000000fb8a74b8\u003e] iomap_iter+0x161/0x1e0\n      [\u003c0000000071dff6ff\u003e] __iomap_dio_rw+0x1df/0x700\n      [\u003c000000002567ba53\u003e] iomap_dio_rw+0x5/0x20\n      [\u003c0000000072e555f8\u003e] btrfs_file_write_iter+0x290/0x530 [btrfs]\n      [\u003c000000005eb3d845\u003e] new_sync_write+0x106/0x180\n      [\u003c000000003fb505bf\u003e] vfs_write+0x24d/0x2f0\n      [\u003c000000009bb57d37\u003e] __x64_sys_pwrite64+0x69/0xa0\n      [\u003c000000003eba3fdf\u003e] do_syscall_64+0x43/0x90\n\nIn case brtfs_qgroup_reserve_data() or btrfs_delalloc_reserve_metadata()\nfail the allocated extent_changeset will not be freed.\n\nSo in btrfs_check_data_free_space() and btrfs_delalloc_reserve_space()\nfree the allocated extent_changeset to get rid of the allocated memory.\n\nThe issue currently only happens in the direct IO write path, but only\nafter 65b3c08606e5 (\"btrfs: fix ENOSPC failure when attempting direct IO\nwrite into NOCOW range\"), and also at defrag_one_locked_target(). Every\nother place is always calling extent_changeset_free() even if its call\nto btrfs_delalloc_reserve_space() or btrfs_check_data_free_space() has\nfailed."
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    "dateReserved": "2024-05-22T06:20:56.206Z",
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