CVE-2024-26984: nouveau: fix instmem race condition around ptr stores
First published: Wed May 01 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: nouveau: fix instmem race condition around ptr stores Running a lot of VK CTS in parallel against nouveau, once every few hours you might see something like this crash. BUG: kernel NULL pointer dereference, address: 0000000000000008 PGD 8000000114e6e067 P4D 8000000114e6e067 PUD 109046067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 7 PID: 53891 Comm: deqp-vk Not tainted 6.8.0-rc6+ #27 Hardware name: Gigabyte Technology Co., Ltd. Z390 I AORUS PRO WIFI/Z390 I AORUS PRO WIFI-CF, BIOS F8 11/05/2021 RIP: 0010:gp100_vmm_pgt_mem+0xe3/0x180 [nouveau] Code: c7 48 01 c8 49 89 45 58 85 d2 0f 84 95 00 00 00 41 0f b7 46 12 49 8b 7e 08 89 da 42 8d 2c f8 48 8b 47 08 41 83 c7 01 48 89 ee <48> 8b 40 08 ff d0 0f 1f 00 49 8b 7e 08 48 89 d9 48 8d 75 04 48 c1 RSP: 0000:ffffac20c5857838 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 00000000004d8001 RCX: 0000000000000001 RDX: 00000000004d8001 RSI: 00000000000006d8 RDI: ffffa07afe332180 RBP: 00000000000006d8 R08: ffffac20c5857ad0 R09: 0000000000ffff10 R10: 0000000000000001 R11: ffffa07af27e2de0 R12: 000000000000001c R13: ffffac20c5857ad0 R14: ffffa07a96fe9040 R15: 000000000000001c FS: 00007fe395eed7c0(0000) GS:ffffa07e2c980000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 000000011febe001 CR4: 00000000003706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ... ? gp100_vmm_pgt_mem+0xe3/0x180 [nouveau] ? gp100_vmm_pgt_mem+0x37/0x180 [nouveau] nvkm_vmm_iter+0x351/0xa20 [nouveau] ? __pfx_nvkm_vmm_ref_ptes+0x10/0x10 [nouveau] ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau] ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau] ? __lock_acquire+0x3ed/0x2170 ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau] nvkm_vmm_ptes_get_map+0xc2/0x100 [nouveau] ? __pfx_nvkm_vmm_ref_ptes+0x10/0x10 [nouveau] ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau] nvkm_vmm_map_locked+0x224/0x3a0 [nouveau] Adding any sort of useful debug usually makes it go away, so I hand wrote the function in a line, and debugged the asm. Every so often pt->memory->ptrs is NULL. This ptrs ptr is set in the nv50_instobj_acquire called from nvkm_kmap. If Thread A and Thread B both get to nv50_instobj_acquire around the same time, and Thread A hits the refcount_set line, and in lockstep thread B succeeds at refcount_inc_not_zero, there is a chance the ptrs value won't have been stored since refcount_set is unordered. Force a memory barrier here, I picked smp_mb, since we want it on all CPUs and it's write followed by a read. v2: use paired smp_rmb/smp_wmb.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/kernel | <5.15.157 | 5.15.157 |
| redhat/kernel | <6.1.88 | 6.1.88 |
| redhat/kernel | <6.6.29 | 6.6.29 |
| redhat/kernel | <6.8.8 | 6.8.8 |
| redhat/kernel | <6.9 | 6.9 |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.112-1 6.11.7-1 6.11.9-1 |
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Reference Links
- https://git.kernel.org/stable/c/13d76b2f443dc371842916dd8768009ff1594716
- https://git.kernel.org/stable/c/1bc4825d4c3ec6abe43cf06c3c39d664d044cbf7
- https://git.kernel.org/stable/c/21ca9539f09360fd83654f78f2c361f2f5ddcb52
- https://git.kernel.org/stable/c/3ab056814cd8ab84744c9a19ef51360b2271c572
- https://git.kernel.org/stable/c/a019b44b1bc6ed224c46fb5f88a8a10dd116e525
- https://git.kernel.org/stable/c/ad74d208f213c06d860916ad40f609ade8c13039
- https://git.kernel.org/stable/c/bba8ec5e9b16649d85bc9e9086bf7ae5b5716ff9
- https://git.kernel.org/stable/c/fff1386cc889d8fb4089d285f883f8cba62d82ce
- https://launchpad.net/bugs/cve/CVE-2024-26984
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-26984
- https://nvd.nist.gov/vuln/detail/CVE-2024-26984
- https://security-tracker.debian.org/tracker/CVE-2024-26984
- https://ubuntu.com/security/CVE-2024-26984
- https://git.kernel.org/linus/fff1386cc889d8fb4089d285f883f8cba62d82ce
- https://access.redhat.com/security/cve/CVE-2024-26984
- https://lore.kernel.org/linux-cve-announce/2024050142-CVE-2024-26984-3028@gregkh/T
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2278334
- https://access.redhat.com/errata/RHSA-2024:9315
- https://access.redhat.com/errata/RHSA-2024:9546
- https://bugzilla.redhat.com/show_bug.cgi?id=2278333
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