CVE-2024-47694

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] ?...