ghsa-q98h-hc6w-gjhg
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
btrfs: scrub: avoid use-after-free when chunk length is not 64K aligned
[BUG] There is a bug report that, on a ext4-converted btrfs, scrub leads to various problems, including:
- "unable to find chunk map" errors BTRFS info (device vdb): scrub: started on devid 1 BTRFS critical (device vdb): unable to find chunk map for logical 2214744064 length 4096 BTRFS critical (device vdb): unable to find chunk map for logical 2214744064 length 45056
This would lead to unrepariable errors.
-
Use-after-free KASAN reports: ================================================================== BUG: KASAN: slab-use-after-free in __blk_rq_map_sg+0x18f/0x7c0 Read of size 8 at addr ffff8881013c9040 by task btrfs/909 CPU: 0 PID: 909 Comm: btrfs Not tainted 6.7.0-x64v3-dbg #11 c50636e9419a8354555555245df535e380563b2b Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 2023.11-2 12/24/2023 Call Trace:
dump_stack_lvl+0x43/0x60 print_report+0xcf/0x640 kasan_report+0xa6/0xd0 __blk_rq_map_sg+0x18f/0x7c0 virtblk_prep_rq.isra.0+0x215/0x6a0 [virtio_blk 19a65eeee9ae6fcf02edfad39bb9ddee07dcdaff] virtio_queue_rqs+0xc4/0x310 [virtio_blk 19a65eeee9ae6fcf02edfad39bb9ddee07dcdaff] blk_mq_flush_plug_list.part.0+0x780/0x860 __blk_flush_plug+0x1ba/0x220 blk_finish_plug+0x3b/0x60 submit_initial_group_read+0x10a/0x290 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] flush_scrub_stripes+0x38e/0x430 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] scrub_stripe+0x82a/0xae0 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] scrub_chunk+0x178/0x200 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] scrub_enumerate_chunks+0x4bc/0xa30 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] btrfs_scrub_dev+0x398/0x810 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] btrfs_ioctl+0x4b9/0x3020 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] __x64_sys_ioctl+0xbd/0x100 do_syscall_64+0x5d/0xe0 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7f47e5e0952b -
Crash, mostly due to above use-after-free
[CAUSE] The converted fs has the following data chunk layout:
item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 2214658048) itemoff 16025 itemsize 80
length 86016 owner 2 stripe_len 65536 type DATA|single
For above logical bytenr 2214744064, it's at the chunk end (2214658048 + 86016 = 2214744064).
This means btrfs_submit_bio() would split the bio, and trigger endio function for both of the two halves.
However scrub_submit_initial_read() would only expect the endio function to be called once, not any more. This means the first endio function would already free the bbio::bio, leaving the bvec freed, thus the 2nd endio call would lead to use-after-free.
[FIX] - Make sure scrub_read_endio() only updates bits in its range Since we may read less than 64K at the end of the chunk, we should not touch the bits beyond chunk boundary.
- Make sure scrub_submit_initial_read() only to read the chunk range This is done by calculating the real number of sectors we need to read, and add sector-by-sector to the bio.
Thankfully the scrub read repair path won't need extra fixes:
- scrub_stripe_submit_repair_read() With above fixes, we won't update error bit for range beyond chunk, thus scrub_stripe_submit_repair_read() should never submit any read beyond the chunk.
{
"affected": [],
"aliases": [
"CVE-2024-26616"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-11T18:15:19Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: scrub: avoid use-after-free when chunk length is not 64K aligned\n\n[BUG]\nThere is a bug report that, on a ext4-converted btrfs, scrub leads to\nvarious problems, including:\n\n- \"unable to find chunk map\" errors\n BTRFS info (device vdb): scrub: started on devid 1\n BTRFS critical (device vdb): unable to find chunk map for logical 2214744064 length 4096\n BTRFS critical (device vdb): unable to find chunk map for logical 2214744064 length 45056\n\n This would lead to unrepariable errors.\n\n- Use-after-free KASAN reports:\n ==================================================================\n BUG: KASAN: slab-use-after-free in __blk_rq_map_sg+0x18f/0x7c0\n Read of size 8 at addr ffff8881013c9040 by task btrfs/909\n CPU: 0 PID: 909 Comm: btrfs Not tainted 6.7.0-x64v3-dbg #11 c50636e9419a8354555555245df535e380563b2b\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 2023.11-2 12/24/2023\n Call Trace:\n \u003cTASK\u003e\n dump_stack_lvl+0x43/0x60\n print_report+0xcf/0x640\n kasan_report+0xa6/0xd0\n __blk_rq_map_sg+0x18f/0x7c0\n virtblk_prep_rq.isra.0+0x215/0x6a0 [virtio_blk 19a65eeee9ae6fcf02edfad39bb9ddee07dcdaff]\n virtio_queue_rqs+0xc4/0x310 [virtio_blk 19a65eeee9ae6fcf02edfad39bb9ddee07dcdaff]\n blk_mq_flush_plug_list.part.0+0x780/0x860\n __blk_flush_plug+0x1ba/0x220\n blk_finish_plug+0x3b/0x60\n submit_initial_group_read+0x10a/0x290 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965]\n flush_scrub_stripes+0x38e/0x430 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965]\n scrub_stripe+0x82a/0xae0 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965]\n scrub_chunk+0x178/0x200 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965]\n scrub_enumerate_chunks+0x4bc/0xa30 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965]\n btrfs_scrub_dev+0x398/0x810 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965]\n btrfs_ioctl+0x4b9/0x3020 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965]\n __x64_sys_ioctl+0xbd/0x100\n do_syscall_64+0x5d/0xe0\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n RIP: 0033:0x7f47e5e0952b\n\n- Crash, mostly due to above use-after-free\n\n[CAUSE]\nThe converted fs has the following data chunk layout:\n\n item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 2214658048) itemoff 16025 itemsize 80\n length 86016 owner 2 stripe_len 65536 type DATA|single\n\nFor above logical bytenr 2214744064, it\u0027s at the chunk end\n(2214658048 + 86016 = 2214744064).\n\nThis means btrfs_submit_bio() would split the bio, and trigger endio\nfunction for both of the two halves.\n\nHowever scrub_submit_initial_read() would only expect the endio function\nto be called once, not any more.\nThis means the first endio function would already free the bbio::bio,\nleaving the bvec freed, thus the 2nd endio call would lead to\nuse-after-free.\n\n[FIX]\n- Make sure scrub_read_endio() only updates bits in its range\n Since we may read less than 64K at the end of the chunk, we should not\n touch the bits beyond chunk boundary.\n\n- Make sure scrub_submit_initial_read() only to read the chunk range\n This is done by calculating the real number of sectors we need to\n read, and add sector-by-sector to the bio.\n\nThankfully the scrub read repair path won\u0027t need extra fixes:\n\n- scrub_stripe_submit_repair_read()\n With above fixes, we won\u0027t update error bit for range beyond chunk,\n thus scrub_stripe_submit_repair_read() should never submit any read\n beyond the chunk.",
"id": "GHSA-q98h-hc6w-gjhg",
"modified": "2024-03-11T18:31:09Z",
"published": "2024-03-11T18:31:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26616"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/34de0f04684ec00c093a0455648be055f0e8e24f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/642b9c520ef2f104277ad1f902f8526edbe087fb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f546c4282673497a06ecb6190b50ae7f6c85b02f"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.