Messages in this thread Patch in this message | | | Date | Mon, 7 Sep 2009 19:45:58 +0530 | From | Kamalesh Babulal <> | Subject | [PATCH] fix error handling in load_module() |
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Hi Rusty,
During our testing following call trace was seen. The testcase was to compile the kernel based on the distro config and try to insert all the modules compiled.
#!/bin/sh
for module in `modprobe -l | tr '\n' ' '` do insert_module=`basename $module .ko` modprobe -v $insert_module done
freq_table sputrace hvcserver axonram pmi ipv6 fuse ehea ib Sep 7 15:46:04 mjs22lp5 kernel: mveth ibmvscsic scsi_transport_srp scsi_tgt Sep 7 15:46:04 mjs22lp5 kernel: NIP: c0000000000ebba0 LR: c0000000000ee79c CTR: 0000000000000000 Sep 7 15:46:04 mjs22lp5 kernel: REGS: c00000002c90b8e0 TRAP: 0700 Tainted: P D (2.6.31-rc8) Sep 7 15:46:04 mjs22lp5 kernel: MSR: 8000000000029032 <EE,ME,CE,IR,DR> CR: 24222488 XER: 00000008 Sep 7 15:46:04 mjs22lp5 kernel: TASK = c00000002ff40000[9062] 'modprobe' THREAD: c00000002c908000 CPU: 0 Sep 7 15:46:04 mjs22lp5 kernel: GPR00: 0000000000000010 c00000002c90bb60 c000000001421e68 0000000000000000 Sep 7 15:46:04 mjs22lp5 kernel: GPR04: c000000000691a5c c00000000009f5c4 0000000000000000 c0000000167f6630 Sep 7 15:46:04 mjs22lp5 kernel: GPR08: c0000000167f72a4 000000000000031f c000000000bb9580 000000000000031e Sep 7 15:46:04 mjs22lp5 kernel: GPR12: 800000000631b800 c0000000015a2600 0000000000000000 0000000000000000 Sep 7 15:46:04 mjs22lp5 kernel: GPR16: 0000000000000033 d00000000fb1f6d0 d00000000fb1fe50 000000000000000e Sep 7 15:46:04 mjs22lp5 kernel: GPR20: d00000000fb1efb8 d00000000fb62260 d00000000fb00000 8000000000000000 Sep 7 15:46:04 mjs22lp5 kernel: GPR24: 0000000000000004 d00000000fb1f190 0000000000000035 fffffffffffffff4 Sep 7 15:46:04 mjs22lp5 kernel: GPR28: 0000000000000000 000000000000031e c00000000137def8 c00000002c90bb60 Sep 7 15:46:04 mjs22lp5 kernel: NIP [c0000000000ebba0] .percpu_modfree+0xe8/0x210 Sep 7 15:46:04 mjs22lp5 kernel: LR [c0000000000ee79c] .load_module+0x14f8/0x1650 Sep 7 15:46:04 mjs22lp5 kernel: Call Trace: Sep 7 15:46:04 mjs22lp5 kernel: [c00000002c90bb60] [c00000002c90bc00] 0xc00000002c90bc00 (unreliable) Sep 7 15:46:04 mjs22lp5 kernel: [c00000002c90bc00] [c0000000000ee79c] .load_module+0x14f8/0x1650 Sep 7 15:46:04 mjs22lp5 kernel: [c00000002c90bd90] [c0000000000ee988] .SyS_init_module+0x94/0x2ac Sep 7 15:46:04 mjs22lp5 kernel: [c00000002c90be30] [c0000000000084dc] syscall_exit+0x0/0x40 Sep 7 15:46:04 mjs22lp5 kernel: Instruction dump: Sep 7 15:46:05 mjs22lp5 kernel: 48000038 e8080006 793d0020 39080004 78090020 2f800000 409c000c 7c0000d0 Sep 7 15:46:05 mjs22lp5 kernel: 78090020 7d4a4a14 393d0001 4200ffb0 <0fe00000> 48000000 38a30001 7f83e378 Sep 7 15:46:05 mjs22lp5 kernel: ---[ end trace 3c8bbdf1034c7f0d ]---
Once the percpu_modalloc fails, percpu_modfree(mod->refptr) is called on a NULL pointer. We try calling it on a NULL pointer. The following patch fixes the problem by introducing a check for mod->refptr before calling percpu_modfree.
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> -- kernel/module.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c index 2d53718..7f89258 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2379,7 +2379,8 @@ static noinline struct module *load_module(void __user *umod, module_unload_free(mod); #if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) free_init: - percpu_modfree(mod->refptr); + if (mod->refptr) + percpu_modfree(mod->refptr); #endif module_free(mod, mod->module_init); free_core: Kamalesh
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