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Subject[PATCH] Fix kobject uevent string handling errors
Fix kobject uevent string handling errors

- increment env->buflen in dmi-id.c
- fix off-by-one in add_uevent_var in error checking of vsnprintf
- add warnings when add_uevent_var. Proper handling of its return values should
really be done by the callers, but they aren't, so things currently
fail silently. This is why I add warnings.

Fixes the following BUG in 2.6.23-rc3-mm1:

[ 23.876358] skb_over_panic: text:c0252e5b len:97 put:11 head:c2b54400 data:c2b54400 tail:0xc2b54461 end:0xc2b54460 dev:<NULL>
[ 23.910278] ------------[ cut here ]------------
[ 23.924080] Kernel BUG at c039e12c [verbose debug info unavailable]
[ 23.942809] invalid opcode: 0000 [#1] PREEMPT SMP
[ 23.957213] last sysfs file: /devices/pci0000:00/0000:00:1f.1/ide0/0.0/media
[ 23.978275] Modules linked in:
[ 23.987429]
[ 23.991884] Pid: 1038, comm: udevtrigger Not tainted (2.6.23-rc3-mm1-testssmp #286)
[ 24.014773] EIP: 0060:[<c039e12c>] EFLAGS: 00010286 CPU: 0
[ 24.031168] EIP is at skb_over_panic+0x5c/0x60
[ 24.044444] EAX: 00000084 EBX: c2b54400 ECX: 00000001 EDX: 00000000
[ 24.063171] ESI: 00000000 EDI: c2b54456 EBP: c2b67eb4 ESP: c2b67e88
[ 24.081895] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[ 24.098027] Process udevtrigger (pid: 1038, ti=c2b66000 task=c2b08030 task.ti=c2b66000)
[ 24.121423] Stack: c050110c c0252e5b 00000061 0000000b c2b54400 c2b54400 c2b54461 c2b54460
[ 24.146658] c04d21e0 c2ad8e80 00000005 c2b67efc c0252e60 c2b54400 c04d2183 c04ce0e4
[ 24.171897] c2f60c40 00000000 c04ce0e4 c2f60c40 c04e2ecb c05401e0 c2f58000 c2b67f04
[ 24.197135] Call Trace:
[ 24.205001] [<c010971a>] show_trace_log_lvl+0x1a/0x30
[ 24.220388] [<c01097d8>] show_stack_log_lvl+0xa8/0xe0
[ 24.235772] [<c01098da>] show_registers+0xca/0x250
[ 24.250378] [<c0109b75>] die+0x115/0x280
[ 24.262389] [<c04187d1>] do_trap+0x91/0xc0
[ 24.274919] [<c0109fc9>] do_invalid_op+0x89/0xa0
[ 24.289004] [<c041858a>] error_code+0x72/0x78
[ 24.302313] [<c0252e60>] kobject_uevent_env+0x370/0x390
[ 24.318217] [<c0252e8a>] kobject_uevent+0xa/0x10
[ 24.332303] [<c02c524b>] store_uevent+0x2b/0x70
[ 24.346130] [<c02c4f6f>] dev_attr_store+0x2f/0x40
[ 24.360476] [<c01cd080>] sysfs_write_file+0xa0/0x100
[ 24.375602] [<c018cb89>] vfs_write+0x99/0x130
[ 24.388910] [<c018d26d>] sys_write+0x3d/0x70
[ 24.401958] [<c0108596>] syscall_call+0x7/0xb
[ 24.415265] =======================
[ 24.425947] INFO: lockdep is turned off.
[ 24.437665] Code: 00 00 89 5c 24 14 8b 98 8c 00 00 00 89 54 24 0c 89 5c 24 10 8b 40 50 89 4c 24 04 c7 04 24 0c 11 50 c0 89 44 24 08 e8 84 20 d9 ff <0f> 0b eb fe 55 89 e5 56 89 d6 53 89 c3 83 ec 0c 8b 40 50 39
[ 24.496006] EIP: [<c039e12c>] skb_over_panic+0x5c/0x60 SS:ESP 0068:c2b67e88
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---
drivers/firmware/dmi-id.c | 5 +++--
lib/kobject_uevent.c | 12 ++++++++++--
2 files changed, 13 insertions(+), 4 deletions(-)
Index: linux-2.6-lttng/lib/kobject_uevent.c
===================================================================
--- linux-2.6-lttng.orig/lib/kobject_uevent.c 2007-08-25 00:07:41.000000000 -0400
+++ linux-2.6-lttng/lib/kobject_uevent.c 2007-08-25 00:12:23.000000000 -0400
@@ -247,8 +247,12 @@ int add_uevent_var(struct kobj_uevent_en
va_list args;
int len;

- if (env->envp_idx >= ARRAY_SIZE(env->envp))
+ if (env->envp_idx >= ARRAY_SIZE(env->envp)) {
+ printk("add_uevent_var: too small array size %u %u\n",
+ env->envp_idx, ARRAY_SIZE(env->envp));
+ WARN_ON(1);
return -ENOMEM;
+ }

va_start(args, format);
len = vsnprintf(&env->buf[env->buflen],
@@ -256,8 +260,12 @@ int add_uevent_var(struct kobj_uevent_en
format, args);
va_end(args);

- if (len + 1 >= (sizeof(env->buf) - env->buflen))
+ if (len >= (sizeof(env->buf) - env->buflen)) {
+ printk("add_uevent_var: failed vsnprintf %d %u\n",
+ len, (sizeof(env->buf) - env->buflen));
+ WARN_ON(1);
return -ENOMEM;
+ }

env->envp[env->envp_idx++] = &env->buf[env->buflen];
env->buflen += len + 1;
Index: linux-2.6-lttng/drivers/firmware/dmi-id.c
===================================================================
--- linux-2.6-lttng.orig/drivers/firmware/dmi-id.c 2007-08-25 00:07:24.000000000 -0400
+++ linux-2.6-lttng/drivers/firmware/dmi-id.c 2007-08-25 00:07:58.000000000 -0400
@@ -152,9 +152,10 @@ static int dmi_dev_uevent(struct device
if (add_uevent_var(env, "MODALIAS="))
return -ENOMEM;
len = get_modalias(&env->buf[env->buflen - 1],
- sizeof(env->buf) - env->buflen);
- if (len >= (sizeof(env->buf) - env->buflen))
+ sizeof(env->buf) - (env->buflen - 1));
+ if (len >= (sizeof(env->buf) - (env->buflen - 1)))
return -ENOMEM;
+ env->buflen += len + 1;
return 0;
}

--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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