4cd482c12b
dev_get_by_index is being called in addr_resolve function which returns NULL and NULL pointer access leads to kernel crash. Following call trace is observed while running rdma_lat test application [ 146.173149] BUG: unable to handle kernel NULL pointer dereference at 00000000000004a0 [ 146.173198] IP: addr_resolve+0x9e/0x3e0 [ib_core] [ 146.173221] PGD 0 P4D 0 [ 146.173869] Oops: 0000 [#1] SMP PTI [ 146.182859] CPU: 8 PID: 127 Comm: kworker/8:1 Tainted: G O 4.15.0-rc6+ #18 [ 146.183758] Hardware name: LENOVO System x3650 M5: -[8871AC1]-/01KN179, BIOS-[TCE132H-2.50]- 10/11/2017 [ 146.184691] Workqueue: ib_cm cm_work_handler [ib_cm] [ 146.185632] RIP: 0010:addr_resolve+0x9e/0x3e0 [ib_core] [ 146.186584] RSP: 0018:ffffc9000362faa0 EFLAGS: 00010246 [ 146.187521] RAX: 000000000000001b RBX: ffffc9000362fc08 RCX: 0000000000000006 [ 146.188472] RDX: 0000000000000000 RSI: 0000000000000096 RDI : ffff88087fc16990 [ 146.189427] RBP: ffffc9000362fb18 R08: 00000000ffffff9d R09: 00000000000004ac [ 146.190392] R10: 00000000000001e7 R11: 0000000000000001 R12: ffff88086af2e090 [ 146.191361] R13: 0000000000000000 R14: 0000000000000001 R15: 00000000ffffff9d [ 146.192327] FS: 0000000000000000(0000) GS:ffff88087fc00000(0000) knlGS:0000000000000000 [ 146.193301] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 146.194274] CR2: 00000000000004a0 CR3: 000000000220a002 CR4: 00000000003606e0 [ 146.195258] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 146.196256] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 146.197231] Call Trace: [ 146.198209] ? rdma_addr_register_client+0x30/0x30 [ib_core] [ 146.199199] rdma_resolve_ip+0x1af/0x280 [ib_core] [ 146.200196] rdma_addr_find_l2_eth_by_grh+0x154/0x2b0 [ib_core] The below patch adds the missing NULL pointer check returned by dev_get_by_index before accessing the netdev to avoid kernel crash. We observed the below crash when we try to do the below test. server client --------- --------- |1.1.1.1|<----rxe-channel--->|1.1.1.2| --------- --------- On server: rdma_lat -c -n 2 -s 1024 On client:rdma_lat 1.1.1.1 -c -n 2 -s 1024 Fixes: 200298326b27 ("IB/core: Validate route when we init ah") Signed-off-by: Muneendra <muneendra.kumar@broadcom.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.