CVE-2025-21888

In the Linux kernel, the following vulnerability has been resolved:

RDMA/mlx5: Fix a WARN during dereg_mr for DM type

Memory regions (MR) of type DM (device memory) do not have an associated umem.

In the _mlx5ibderegmr() -> mlx5freeprivdescs() flow, the code incorrectly takes the wrong branch, attempting to call dmaunmap_single() on a DMA address that is not mapped.

This results in a WARN [1], as shown below.

The issue is resolved by properly accounting for the DM type and ensuring the correct branch is selected in mlx5freepriv_descs().

[1] WARNING: CPU: 12 PID: 1346 at drivers/iommu/dma-iommu.c:1230 iommudmaunmappage+0x79/0x90 Modules linked in: ip6tablemangle ip6tablenat ip6tablefilter ip6tables iptablemangle xtconntrack xtMASQUERADE nfconntracknetlink nfnetlink xtaddrtype iptablenat nfnat brnetfilter rpcsecgsskrb5 authrpcgss oidregistry ovelay rpcrdma rdmaucm ibiser libiscsi scsitransportiscsi ibumad rdmacm ibipoib iwcm ibcm mlx5ib ibuverbs ibcore fuse mlx5core CPU: 12 UID: 0 PID: 1346 Comm: ibvrcpingpong Not tainted 6.12.0-rc7+ #1631 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:iommudmaunmappage+0x79/0x90 Code: 2b 49 3b 29 72 26 49 3b 69 08 73 20 4d 89 f0 44 89 e9 4c 89 e2 48 89 ee 48 89 df 5b 5d 41 5c 41 5d 41 5e 41 5f e9 07 b8 88 ff <0f> 0b 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 66 0f 1f 44 00 RSP: 0018:ffffc90001913a10 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88810194b0a8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001 RBP: ffff88810194b0a8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f537abdd740(0000) GS:ffff88885fb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f537aeb8000 CR3: 000000010c248001 CR4: 0000000000372eb0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? _warn+0x84/0x190 ? iommudmaunmappage+0x79/0x90 ? reportbug+0xf8/0x1c0 ? handlebug+0x55/0x90 ? excinvalidop+0x13/0x60 ? asmexcinvalidop+0x16/0x20 ? iommudmaunmappage+0x79/0x90 dmaunmappageattrs+0xe6/0x290 mlx5freeprivdescs+0xb0/0xe0 [mlx5ib] _mlx5ibderegmr+0x37e/0x520 [mlx5ib] ? rawspinunlockirq+0x24/0x40 ? waitforcompletion+0xfe/0x130 ? rdmarestrackput+0x63/0xe0 [ibcore] ibderegmruser+0x5f/0x120 [ibcore] ? lockrelease+0xc6/0x280 destroyhwidruobject+0x1d/0x60 [ibuverbs] uverbsdestroyuobject+0x58/0x1d0 [ibuverbs] uobjdestroy+0x3f/0x70 [ibuverbs] ibuverbscmdverbs+0x3e4/0xbb0 [ibuverbs] ? _pfxuverbsdestroydefhandler+0x10/0x10 [ibuverbs] ? lockacquire+0xc1/0x2f0 ? ibuverbsioctl+0xcb/0x170 [ibuverbs] ? ibuverbsioctl+0x116/0x170 [ibuverbs] ? lockrelease+0xc6/0x280 ibuverbsioctl+0xe7/0x170 [ibuverbs] ? ibuverbsioctl+0xcb/0x170 [ibuverbs] _x64sysioctl+0x1b0/0xa70 dosyscall64+0x6b/0x140 entrySYSCALL64afterhwframe+0x76/0x7e RIP: 0033:0x7f537adaf17b Code: 0f 1e fa 48 8b 05 1d ad 0c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ed ac 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffff218f0b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffff218f1d8 RCX: 00007f537adaf17b RDX: 00007ffff218f1c0 RSI: 00000000c0181b01 RDI: 0000000000000003 RBP: 00007ffff218f1a0 R08: 00007f537aa8d010 R09: 0000561ee2e4f270 R10: 00007f537aace3a8 R11: 0000000000000246 R12: 00007ffff218f190 R13: 000000000000001c R14: 0000561ee2e4d7c0 R15: 00007ffff218f450 </TASK>