From: Mike Marciniszyn mike.marciniszyn@intel.com
There are config dependent code paths that expose panics in unload paths both in this file and in debugfs_remove_recursive() because CONFIG_FAULT_INJECTION and CONFIG_FAULT_INJECTION_DEBUG_FS can be set independently.
Having CONFIG_FAULT_INJECTION set and CONFIG_FAULT_INJECTION_DEBUG_FS reset causes fault_create_debugfs_attr() to return an error.
The debugfs.c routines tolerate failures, but the module unload panics dereferencing a NULL in the two exit routines. If that is fixed, the dir passed to debugfs_remove_recursive comes from a memory location that was freed and potentially reused causing a segfault or corrupting memory.
Here is an example of the NULL deref panic:
[66866.286829] BUG: unable to handle kernel NULL pointer dereference at 0000000000000088 [66866.295602] IP: hfi1_dbg_ibdev_exit+0x2a/0x80 [hfi1] [66866.301138] PGD 858496067 P4D 858496067 PUD 8433a7067 PMD 0 [66866.307452] Oops: 0000 [#1] SMP [66866.310953] Modules linked in: hfi1(-) rdmavt rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm iw_cm ib_cm ib_core rpcsec_gss_krb5 nfsv4 dns_resolver nfsv3 nfs fscache sb_edac x86_pkg_temp_thermal intel_powerclamp vfat fat coretemp kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel iTCO_wdt iTCO_vendor_support crypto_simd mei_me glue_helper cryptd mxm_wmi ipmi_si pcspkr lpc_ich sg mei ioatdma ipmi_devintf i2c_i801 mfd_core shpchp ipmi_msghandler wmi acpi_power_meter acpi_cpufreq nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables ext4 mbcache jbd2 sd_mod mgag200 drm_kms_helper syscopyarea sysfillrect sysimgblt igb fb_sys_fops ttm ahci ptp crc32c_intel libahci pps_core drm dca libata i2c_algo_bit i2c_core [last unloaded: opa_vnic] [66866.385551] CPU: 8 PID: 7470 Comm: rmmod Not tainted 4.14.0-mam-tid-rdma #2 [66866.393317] Hardware name: Intel Corporation S2600WT2/S2600WT2, BIOS SE5C610.86B.01.01.0018.C4.072020161249 07/20/2016 [66866.405252] task: ffff88084f28c380 task.stack: ffffc90008454000 [66866.411866] RIP: 0010:hfi1_dbg_ibdev_exit+0x2a/0x80 [hfi1] [66866.417984] RSP: 0018:ffffc90008457da0 EFLAGS: 00010202 [66866.423812] RAX: 0000000000000000 RBX: ffff880857de0000 RCX: 0000000180040001 [66866.431773] RDX: 0000000180040002 RSI: ffffea0021088200 RDI: 0000000040000000 [66866.439734] RBP: ffffc90008457da8 R08: ffff88084220e000 R09: 0000000180040001 [66866.447696] R10: 000000004220e001 R11: ffff88084220e000 R12: ffff88085a31c000 [66866.455657] R13: ffffffffa07c9820 R14: ffffffffa07c9890 R15: ffff881059d78100 [66866.463618] FS: 00007f6876047740(0000) GS:ffff88085f800000(0000) knlGS:0000000000000000 [66866.472644] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [66866.479053] CR2: 0000000000000088 CR3: 0000000856357006 CR4: 00000000001606e0 [66866.487013] Call Trace: [66866.489747] remove_one+0x1f/0x220 [hfi1] [66866.494221] pci_device_remove+0x39/0xc0 [66866.498596] device_release_driver_internal+0x141/0x210 [66866.504424] driver_detach+0x3f/0x80 [66866.508409] bus_remove_driver+0x55/0xd0 [66866.512784] driver_unregister+0x2c/0x50 [66866.517164] pci_unregister_driver+0x2a/0xa0 [66866.521934] hfi1_mod_cleanup+0x10/0xaa2 [hfi1] [66866.526988] SyS_delete_module+0x171/0x250 [66866.531558] do_syscall_64+0x67/0x1b0 [66866.535644] entry_SYSCALL64_slow_path+0x25/0x25 [66866.540792] RIP: 0033:0x7f6875525c27 [66866.544777] RSP: 002b:00007ffd48528e78 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 [66866.553224] RAX: ffffffffffffffda RBX: 0000000001cc01d0 RCX: 00007f6875525c27 [66866.561185] RDX: 00007f6875596000 RSI: 0000000000000800 RDI: 0000000001cc0238 [66866.569146] RBP: 0000000000000000 R08: 00007f68757e9060 R09: 00007f6875596000 [66866.577120] R10: 00007ffd48528c00 R11: 0000000000000206 R12: 00007ffd48529db4 [66866.585080] R13: 0000000000000000 R14: 0000000001cc01d0 R15: 0000000001cc0010 [66866.593040] Code: 90 0f 1f 44 00 00 48 83 3d a3 8b 03 00 00 55 48 89 e5 53 48 89 fb 74 4e 48 8d bf 18 0c 00 00 e8 9d f2 ff ff 48 8b 83 20 0c 00 00 <48> 8b b8 88 00 00 00 e8 2a 21 b3 e0 48 8b bb 20 0c 00 00 e8 0e [66866.614127] RIP: hfi1_dbg_ibdev_exit+0x2a/0x80 [hfi1] RSP: ffffc90008457da0 [66866.621885] CR2: 0000000000000088 [66866.625618] ---[ end trace c4817425783fb092 ]---
Fix by insuring that upon failure from fault_create_debugfs_attr() the parent pointer for the routines is always set to NULL and guards added in the exit routines to insure that debugfs_remove_recursive() is not called when when the parent pointer is NULL.
Fixes: 0181ce31b260 ("IB/hfi1: Add receive fault injection feature") Cc: stable@vger.kernel.org # 4.14.x Reviewed-by: Michael J. Ruhl michael.j.ruhl@intel.com Signed-off-by: Mike Marciniszyn mike.marciniszyn@intel.com Signed-off-by: Dennis Dalessandro dennis.dalessandro@intel.com --- drivers/infiniband/hw/hfi1/debugfs.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/hw/hfi1/debugfs.c b/drivers/infiniband/hw/hfi1/debugfs.c index 852173b..5343960 100644 --- a/drivers/infiniband/hw/hfi1/debugfs.c +++ b/drivers/infiniband/hw/hfi1/debugfs.c @@ -1227,7 +1227,8 @@ static int _fault_stats_seq_show(struct seq_file *s, void *v)
static void fault_exit_opcode_debugfs(struct hfi1_ibdev *ibd) { - debugfs_remove_recursive(ibd->fault_opcode->dir); + if (ibd->fault_opcode) + debugfs_remove_recursive(ibd->fault_opcode->dir); kfree(ibd->fault_opcode); ibd->fault_opcode = NULL; } @@ -1255,6 +1256,7 @@ static int fault_init_opcode_debugfs(struct hfi1_ibdev *ibd) &ibd->fault_opcode->attr); if (IS_ERR(ibd->fault_opcode->dir)) { kfree(ibd->fault_opcode); + ibd->fault_opcode = NULL; return -ENOENT; }
@@ -1278,7 +1280,8 @@ static int fault_init_opcode_debugfs(struct hfi1_ibdev *ibd)
static void fault_exit_packet_debugfs(struct hfi1_ibdev *ibd) { - debugfs_remove_recursive(ibd->fault_packet->dir); + if (ibd->fault_packet) + debugfs_remove_recursive(ibd->fault_packet->dir); kfree(ibd->fault_packet); ibd->fault_packet = NULL; } @@ -1304,6 +1307,7 @@ static int fault_init_packet_debugfs(struct hfi1_ibdev *ibd) &ibd->fault_opcode->attr); if (IS_ERR(ibd->fault_packet->dir)) { kfree(ibd->fault_packet); + ibd->fault_packet = NULL; return -ENOENT; }