2012-06-22 17:14:57

by Johannes Berg

Subject: [PATCH] compat-wireless: add patch to fix iwlwifi tracing

From: Johannes Berg <[email protected]>

See the description in the file -- the current code
is safe only on recent upstream kernels, with 3.1
for example it can crash. The new code is safe on
all kernels that even support %pV, others just get
a pointer unfortunately.

Signed-off-by: Johannes Berg <[email protected]>
---
patches/55-iwlwifi-msg-trace-fix.patch | 70 ++++++++++++++++++++++++++++++++
1 file changed, 70 insertions(+)
create mode 100644 patches/55-iwlwifi-msg-trace-fix.patch

diff --git a/patches/55-iwlwifi-msg-trace-fix.patch b/patches/55-iwlwifi-msg-trace-fix.patch
new file mode 100644
index 0000000..1e8803f
--- /dev/null
+++ b/patches/55-iwlwifi-msg-trace-fix.patch
@@ -0,0 +1,70 @@
+In recent kernels, %pV will copy the va_list before using it.
+This isn't true for all kernels, so copy the va_list for use
+by the dev_*() functions, otherwise the kernel will crash if
+the message is printed and traced.
+
+--- a/drivers/net/wireless/iwlwifi/iwl-debug.c
++++ b/drivers/net/wireless/iwlwifi/iwl-debug.c
+@@ -72,13 +72,16 @@ void __iwl_ ##fn(struct device *dev, const char *fmt, ...) \
+ struct va_format vaf = { \
+ .fmt = fmt, \
+ }; \
+- va_list args; \
++ va_list args1, args2; \
+ \
+- va_start(args, fmt); \
+- vaf.va = &args; \
++ va_start(args1, fmt); \
++ va_copy(args2, args1); \
++ vaf.va = &args2; \
+ dev_ ##fn(dev, "%pV", &vaf); \
++ va_end(args2); \
++ vaf.va = &args1; \
+ trace_iwlwifi_ ##fn(&vaf); \
+- va_end(args); \
++ va_end(args1); \
+ }
+
+ __iwl_fn(warn)
+@@ -97,13 +100,18 @@ void __iwl_err(struct device *dev, bool rfkill_prefix, bool trace_only,
+ va_list args;
+
+ va_start(args, fmt);
+- vaf.va = &args;
+ if (!trace_only) {
++ va_list args2;
++
++ va_copy(args2, args);
++ vaf.va = &args2;
+ if (rfkill_prefix)
+ dev_err(dev, "(RFKILL) %pV", &vaf);
+ else
+ dev_err(dev, "%pV", &vaf);
++ va_end(args2);
+ }
++ vaf.va = &args;
+ trace_iwlwifi_err(&vaf);
+ va_end(args);
+ }
+@@ -120,13 +128,19 @@ void __iwl_dbg(struct device *dev,
+ va_list args;
+
+ va_start(args, fmt);
+- vaf.va = &args;
+ #ifdef CONFIG_IWLWIFI_DEBUG
+ if (iwl_have_debug_level(level) &&
+- (!limit || net_ratelimit()))
++ (!limit || net_ratelimit())) {
++ va_list args2;
++
++ va_copy(args2, args);
++ vaf.va = &args2;
+ dev_err(dev, "%c %s %pV", in_interrupt() ? 'I' : 'U',
+ function, &vaf);
++ va_end(args2);
++ }
+ #endif
++ vaf.va = &args;
+ trace_iwlwifi_dbg(level, in_interrupt(), function, &vaf);
+ va_end(args);
+ }
--
1.7.10

2012-06-22 17:27:23

by Luis R. Rodriguez

Subject: Re: [PATCH] compat-wireless: add patch to fix iwlwifi tracing

On Fri, Jun 22, 2012 at 10:14 AM, Johannes Berg
<[email protected]> wrote:
> From: Johannes Berg <[email protected]>
>
> See the description in the file -- the current code
> is safe only on recent upstream kernels, with 3.1
> for example it can crash. The new code is safe on
> all kernels that even support %pV, others just get
> a pointer unfortunately.
>
> Signed-off-by: Johannes Berg <[email protected]>

Applied and pushed!

Luis