# CVE-2024-46687: linux: In the Linux kernel, the following vulnerability has been resolved: btrfs: fix a use-after-free when hitting errors... CVE-2024-46687 is fixed in 26 products on 1 platform, first by DEBIAN-CVE-2024-46687, released September 13, 2024. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2024-46687 - Priority: High - CVSS: 7.8 (high) - EPSS: 0.0021 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 13, 2024 ## Description In the Linux kernel, the following vulnerability has been resolved: btrfs: fix a use-after-free when hitting errors inside btrfs_submit_chunk() [BUG] There is an internal report that KASAN is reporting use-after-free, with the following backtrace: BUG: KASAN: slab-use-after-free in btrfs_check_read_bio+0xa68/0xb70 [btrfs] Read of size 4 at addr ffff8881117cec28 by task kworker/u16:2/45 CPU: 1 UID: 0 PID: 45 Comm: kworker/u16:2 Not tainted 6.11.0-rc2-next-20240805-default+ #76 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014 Workqueue: btrfs-endio btrfs_end_bio_work [btrfs] Call Trace: dump_stack_lvl+0x61/0x80 print_address_description.constprop.0+0x5e/0x2f0 print_report+0x118/0x216 kasan_report+0x11d/0x1f0 btrfs_check_read_bio+0xa68/0xb70 [btrfs] process_one_work+0xce0/0x12a0 worker_thread+0x717/0x1250 kthread+0x2e3/0x3c0 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x11/0x20 Allocated by task 20917: kasan_save_stack+0x37/0x60 kasan_save_track+0x10/0x30 __kasan_slab_alloc+0x7d/0x80 kmem_cache_alloc_noprof+0x16e/0x3e0 mempool_alloc_noprof+0x12e/0x310 bio_alloc_bioset+0x3f0/0x7a0 btrfs_bio_alloc+0x2e/0x50 [btrfs] submit_extent_page+0x4d1/0xdb0 [btrfs] btrfs_do_readpage+0x8b4/0x12a0 [btrfs] btrfs_readahead+0x29a/0x430 [btrfs] read_pages+0x1a7/0xc60 page_cache_ra_unbounded+0x2ad/0x560 filemap_get_pages+0x629/0xa20 filemap_read+0x335/0xbf0 vfs_read+0x790/0xcb0 ksys_read+0xfd/0x1d0 do_syscall_64+0x6d/0x140 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Freed by task 20917: kasan_save_stack+0x37/0x60 kasan_save_track+0x10/0x30 kasan_save_free_info+0x37/0x50 __kasan_slab_free+0x4b/0x60 kmem_cache_free+0x214/0x5d0 bio_free+0xed/0x180 end_bbio_data_read+0x1cc/0x580 [btrfs] btrfs_submit_chunk+0x98d/0x1880 [btrfs] btrfs_submit_bio+0x33/0x70 [btrfs] submit_one_bio+0xd4/0x130 [btrfs] submit_extent_page+0x3ea/0xdb0 [btrfs] btrfs_do_readpage+0x8b4/0x12a0 [btrfs] btrfs_readahead+0x29a/0x430 [btrfs] read_pages+0x1a7/0xc60 page_cache_ra_unbounded+0x2ad/0x560 filemap_get_pages+0x629/0xa20 filemap_read+0x335/0xbf0 vfs_read+0x790/0xcb0 ksys_read+0xfd/0x1d0 do_syscall_64+0x6d/0x140 entry_SYSCALL_64_after_hwframe+0x4b/0x53 [CAUSE] Although I cannot reproduce the error, the report itself is good enough to pin down the cause. The call trace is the regular endio workqueue context, but the free-by-task trace is showing that during btrfs_submit_chunk() we already hit a critical error, and is calling btrfs_bio_end_io() to error out. And the original endio function called bio_put() to free the whole bio. This means a double freeing thus causing use-after-free, e.g.: 1. Enter btrfs_submit_bio() with a read bio The read bio length is 128K, crossing two 64K stripes. 2. The first run of btrfs_submit_chunk() 2.1 Call btrfs_map_block(), which returns 64K 2.2 Call btrfs_split_bio() Now there are two bios, one referring to the first 64K, the other referring to the second 64K. 2.3 The first half is submitted. 3. The second run of btrfs_submit_chunk() 3.1 Call btrfs_map_block(), which by somehow failed Now we call btrfs_bio_end_io() to handle the error 3.2 btrfs_bio_end_io() calls the original endio function Which is end_bbio_data_read(), and it calls bio_put() for the original bio. Now the original bio is freed. 4. The submitted first 64K bio finished Now we call into btrfs_check_read_bio() and tries to advance the bio iter. But since the original bio (thus its iter) is already freed, we trigger the above use-after free. And even if the memory is not poisoned/corrupted, we will later call the original endio function, causing a double freeing. [FIX] Instead of calling btrfs_bio_end_io(), call btrfs_orig_bbio_end_io(), which has the extra check on split bios and do the pr ---truncated--- ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | dtb-aarch64 opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-64kb opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-64kb sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-azure opensuse-leap 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 | | Linux | kernel-azure sles 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 | | Linux | kernel-coco sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 | | Linux | kernel-coco_debug sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 | | Linux | kernel-debug opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-default opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-default sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-default-base opensuse-leap 15.6 | 6.4.0-150600.23.25.1.150600.12.10.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-default-base sles 15.6 | 6.4.0-150600.23.25.1.150600.12.10.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-docs opensuse-leap 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-docs sles 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-kvmsmall opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-livepatch-SLE15-SP6-RT_Update_4 sles 15.6 | 1-150600.1.3.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 | | Linux | kernel-livepatch-SLE15-SP6_Update_5 sles 15.6 | 1-150600.13.3.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-obs-build opensuse-leap 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-obs-build sles 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-obs-qa opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-rt opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 | | Linux | kernel-rt_debug opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 | | Linux | kernel-source opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-source sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-source-azure opensuse-leap 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 | | Linux | kernel-source-azure sles 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 | | Linux | kernel-source-coco sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 | | Linux | kernel-source-rt opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 | | Linux | kernel-syms opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-syms sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-syms-azure opensuse-leap 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 | | Linux | kernel-syms-azure sles 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 | | Linux | kernel-syms-coco sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 | | Linux | kernel-syms-rt opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 | | Linux | kernel-zfcpdump opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | kernel-zfcpdump sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 | | Linux | linux Debian 13.5 (trixie) | 6.10.9-1 | [DEBIAN-CVE-2024-46687](https://patchblox.com/security/data/fix/linux/debian-cve-2024-46687.md) | Sep 13, 2024 | | Linux | linux Debian 14 | 6.10.9-1 | [DEBIAN-CVE-2024-46687](https://patchblox.com/security/data/fix/linux/debian-cve-2024-46687.md) | Sep 13, 2024 | --- Data as of 2026-11-08T13:06:02Z UTC. 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