Subject: CVE-2024-47694: IB/mlx5: Fix UMR pd cleanup on error flow of driver init

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

IB/mlx5: Fix UMR pd cleanup on error flow of driver init

The cited commit moves the pd allocation from function
mlx5r_umr_resource_cleanup() to a new function mlx5r_umr_cleanup().
So the fix in commit [1] is broken. In error flow, will hit panic [2].

Fix it by checking pd pointer to avoid panic if it is NULL;

[1] RDMA/mlx5: Fix UMR cleanup on error flow of driver init
[2]
 [  347.567063] infiniband mlx5_0: Couldn't register device with driver model
 [  347.591382] BUG: kernel NULL pointer dereference, address: 0000000000000020
 [  347.593438] #PF: supervisor read access in kernel mode
 [  347.595176] #PF: error_code(0x0000) - not-present page
 [  347.596962] PGD 0 P4D 0
 [  347.601361] RIP: 0010:ib_dealloc_pd_user+0x12/0xc0 [ib_core]
 [  347.604171] RSP: 0018:ffff888106293b10 EFLAGS: 00010282
 [  347.604834] RAX: 0000000000000000 RBX: 000000000000000e RCX: 0000000000000000
 [  347.605672] RDX: ffff888106293ad0 RSI: 0000000000000000 RDI: 0000000000000000
 [  347.606529] RBP: 0000000000000000 R08: ffff888106293ae0 R09: ffff888106293ae0
 [  347.607379] R10: 0000000000000a06 R11: 0000000000000000 R12: 0000000000000000
 [  347.608224] R13: ffffffffa0704dc0 R14: 0000000000000001 R15: 0000000000000001
 [  347.609067] FS:  00007fdc720cd9c0(0000) GS:ffff88852c880000(0000) knlGS:0000000000000000
 [  347.610094] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 [  347.610727] CR2: 0000000000000020 CR3: 0000000103012003 CR4: 0000000000370eb0
 [  347.611421] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 [  347.612113] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 [  347.612804] Call Trace:
 [  347.613130]  <TASK>
 [  347.613417]  ? __die+0x20/0x60
 [  347.613793]  ? page_fault_oops+0x150/0x3e0
 [  347.614243]  ? free_msg+0x68/0x80 [mlx5_core]
 [  347.614840]  ? cmd_exec+0x48f/0x11d0 [mlx5_core]
 [  347.615359]  ? exc_page_fault+0x74/0x130
 [  347.615808]  ? asm_exc_page_fault+0x22/0x30
 [  347.616273]  ? ib_dealloc_pd_user+0x12/0xc0 [ib_core]
 [  347.616801]  mlx5r_umr_cleanup+0x23/0x90 [mlx5_ib]
 [  347.617365]  mlx5_ib_stage_pre_ib_reg_umr_cleanup+0x36/0x40 [mlx5_ib]
 [  347.618025]  __mlx5_ib_add+0x96/0xd0 [mlx5_ib]
 [  347.618539]  mlx5r_probe+0xe9/0x310 [mlx5_ib]
 [  347.619032]  ? kernfs_add_one+0x107/0x150
 [  347.619478]  ? __mlx5_ib_add+0xd0/0xd0 [mlx5_ib]
 [  347.619984]  auxiliary_bus_probe+0x3e/0x90
 [  347.620448]  really_probe+0xc5/0x3a0
 [  347.620857]  __driver_probe_device+0x80/0x160
 [  347.621325]  driver_probe_device+0x1e/0x90
 [  347.621770]  __driver_attach+0xec/0x1c0
 [  347.622213]  ? __device_attach_driver+0x100/0x100
 [  347.622724]  bus_for_each_dev+0x71/0xc0
 [  347.623151]  bus_add_driver+0xed/0x240
 [  347.623570]  driver_register+0x58/0x100
 [  347.623998]  __auxiliary_driver_register+0x6a/0xc0
 [  347.624499]  ? driver_register+0xae/0x100
 [  347.624940]  ? 0xffffffffa0893000
 [  347.625329]  mlx5_ib_init+0x16a/0x1e0 [mlx5_ib]
 [  347.625845]  do_one_initcall+0x4a/0x2a0
 [  347.626273]  ? gcov_event+0x2e2/0x3a0
 [  347.626706]  do_init_module+0x8a/0x260
 [  347.627126]  init_module_from_file+0x8b/0xd0
 [  347.627596]  __x64_sys_finit_module+0x1ca/0x2f0
 [  347.628089]  do_syscall_64+0x4c/0x100

The Linux kernel CVE team has assigned CVE-2024-47694 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 6.11 with commit 638420115cc4 and fixed in 6.11.2 with commit 99e2de5942b0
	Issue introduced in 6.11 with commit 638420115cc4 and fixed in 6.12-rc1 with commit 112e6e83a894

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-47694
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/infiniband/hw/mlx5/umr.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/99e2de5942b0390ddc24efada71edc6593e23f05
	https://git.kernel.org/stable/c/112e6e83a894260cc7efe79a1fc47d4d51461742