FAILED: patch "[PATCH] tracing/kprobes: Return EADDRNOTAVAIL when func matches" failed to apply to 4.19-stable tree

FAILED: patch "[PATCH] tracing/kprobes: Return EADDRNOTAVAIL when func matches" failed to apply to 4.19-stable tree

[gregkh]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x b022f0c7e404887a7c5229788fc99eff9f9a80d5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023102138-riverbed-senator-e356@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b022f0c7e404887a7c5229788fc99eff9f9a80d5 Mon Sep 17 00:00:00 2001
From: Francis Laniel <flaniel@linux.microsoft.com>
Date: Fri, 20 Oct 2023 13:42:49 +0300
Subject: [PATCH] tracing/kprobes: Return EADDRNOTAVAIL when func matches
 several symbols

When a kprobe is attached to a function that's name is not unique (is
static and shares the name with other functions in the kernel), the
kprobe is attached to the first function it finds. This is a bug as the
function that it is attaching to is not necessarily the one that the
user wants to attach to.

Instead of blindly picking a function to attach to what is ambiguous,
error with EADDRNOTAVAIL to let the user know that this function is not
unique, and that the user must use another unique function with an
address offset to get to the function they want to attach to.

Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/

Cc: stable@vger.kernel.org
Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 3d7a180a8427..a8fef6ab0872 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -705,6 +705,25 @@ static struct notifier_block trace_kprobe_module_nb = {
 	.priority = 1	/* Invoked after kprobe module callback */
 };
 
+static int count_symbols(void *data, unsigned long unused)
+{
+	unsigned int *count = data;
+
+	(*count)++;
+
+	return 0;
+}
+
+static unsigned int number_of_same_symbols(char *func_name)
+{
+	unsigned int count;
+
+	count = 0;
+	kallsyms_on_each_match_symbol(count_symbols, func_name, &count);
+
+	return count;
+}
+
 static int __trace_kprobe_create(int argc, const char *argv[])
 {
 	/*
@@ -836,6 +855,31 @@ static int __trace_kprobe_create(int argc, const char *argv[])
 		}
 	}
 
+	if (symbol && !strchr(symbol, ':')) {
+		unsigned int count;
+
+		count = number_of_same_symbols(symbol);
+		if (count > 1) {
+			/*
+			 * Users should use ADDR to remove the ambiguity of
+			 * using KSYM only.
+			 */
+			trace_probe_log_err(0, NON_UNIQ_SYMBOL);
+			ret = -EADDRNOTAVAIL;
+
+			goto error;
+		} else if (count == 0) {
+			/*
+			 * We can return ENOENT earlier than when register the
+			 * kprobe.
+			 */
+			trace_probe_log_err(0, BAD_PROBE_ADDR);
+			ret = -ENOENT;
+
+			goto error;
+		}
+	}
+
 	trace_probe_log_set_index(0);
 	if (event) {
 		ret = traceprobe_parse_event_name(&event, &group, gbuf,
@@ -1695,6 +1739,7 @@ static int unregister_kprobe_event(struct trace_kprobe *tk)
 }
 
 #ifdef CONFIG_PERF_EVENTS
+
 /* create a trace_kprobe, but don't add it to global lists */
 struct trace_event_call *
 create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
@@ -1705,6 +1750,24 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
 	int ret;
 	char *event;
 
+	if (func) {
+		unsigned int count;
+
+		count = number_of_same_symbols(func);
+		if (count > 1)
+			/*
+			 * Users should use addr to remove the ambiguity of
+			 * using func only.
+			 */
+			return ERR_PTR(-EADDRNOTAVAIL);
+		else if (count == 0)
+			/*
+			 * We can return ENOENT earlier than when register the
+			 * kprobe.
+			 */
+			return ERR_PTR(-ENOENT);
+	}
+
 	/*
 	 * local trace_kprobes are not added to dyn_event, so they are never
 	 * searched in find_trace_kprobe(). Therefore, there is no concern of
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 02b432ae7513..850d9ecb6765 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -450,6 +450,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	C(BAD_MAXACT,		"Invalid maxactive number"),		\
 	C(MAXACT_TOO_BIG,	"Maxactive is too big"),		\
 	C(BAD_PROBE_ADDR,	"Invalid probed address or symbol"),	\
+	C(NON_UNIQ_SYMBOL,	"The symbol is not unique"),		\
 	C(BAD_RETPROBE,		"Retprobe address must be an function entry"), \
 	C(NO_TRACEPOINT,	"Tracepoint is not found"),		\
 	C(BAD_ADDR_SUFFIX,	"Invalid probed address suffix"), \

[PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Francis Laniel]

When a kprobe is attached to a function that's name is not unique (is
static and shares the name with other functions in the kernel), the
kprobe is attached to the first function it finds. This is a bug as the
function that it is attaching to is not necessarily the one that the
user wants to attach to.

Instead of blindly picking a function to attach to what is ambiguous,
error with EADDRNOTAVAIL to let the user know that this function is not
unique, and that the user must use another unique function with an
address offset to get to the function they want to attach to.

Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/

Cc: stable@vger.kernel.org
Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
(cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
---
 kernel/trace/trace_kprobe.c | 48 +++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 36dfea29d5fa..720110942505 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -715,6 +715,36 @@ static inline void sanitize_event_name(char *name)
 			*name = '_';
 }
 
+struct count_symbols_struct {
+	const char *func_name;
+	unsigned int count;
+};
+
+static int count_symbols(void *data, const char *name, struct module *unused0,
+			 unsigned long unused1)
+{
+	struct count_symbols_struct *args = data;
+
+	if (strcmp(args->func_name, name))
+		return 0;
+
+	args->count++;
+
+	return 0;
+}
+
+static unsigned int number_of_same_symbols(char *func_name)
+{
+	struct count_symbols_struct args = {
+		.func_name = func_name,
+		.count = 0,
+	};
+
+	kallsyms_on_each_symbol(count_symbols, &args);
+
+	return args.count;
+}
+
 static int create_trace_kprobe(int argc, char **argv)
 {
 	/*
@@ -845,6 +875,24 @@ static int create_trace_kprobe(int argc, char **argv)
 	}
 	argc -= 2; argv += 2;
 
+	if (symbol && !strchr(symbol, ':')) {
+		unsigned int count;
+
+		count = number_of_same_symbols(symbol);
+		if (count > 1)
+			/*
+			 * Users should use ADDR to remove the ambiguity of
+			 * using KSYM only.
+			 */
+			return -EADDRNOTAVAIL;
+		else if (count == 0)
+			/*
+			 * We can return ENOENT earlier than when register the
+			 * kprobe.
+			 */
+			return -ENOENT;
+	}
+
 	/* setup a probe */
 	if (!event) {
 		/* Make a new event name */
-- 
2.34.1

Re: [PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Greg KH]

On Fri, Nov 24, 2023 at 01:24:13PM +0100, Francis Laniel wrote:
> When a kprobe is attached to a function that's name is not unique (is
> static and shares the name with other functions in the kernel), the
> kprobe is attached to the first function it finds. This is a bug as the
> function that it is attaching to is not necessarily the one that the
> user wants to attach to.
> 
> Instead of blindly picking a function to attach to what is ambiguous,
> error with EADDRNOTAVAIL to let the user know that this function is not
> unique, and that the user must use another unique function with an
> address offset to get to the function they want to attach to.
> 
> Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/
> 
> Cc: stable@vger.kernel.org
> Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
> Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
> Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/
> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> (cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
> ---
>  kernel/trace/trace_kprobe.c | 48 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)

Again, we need a version for 5.4.y as well before we can take this
version.

thanks,

greg k-h

Re: [PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Francis Laniel]

Hi!


Le vendredi 24 novembre 2023, 17:17:04 CET Greg KH a écrit :
> On Fri, Nov 24, 2023 at 01:24:13PM +0100, Francis Laniel wrote:
> > When a kprobe is attached to a function that's name is not unique (is
> > static and shares the name with other functions in the kernel), the
> > kprobe is attached to the first function it finds. This is a bug as the
> > function that it is attaching to is not necessarily the one that the
> > user wants to attach to.
> > 
> > Instead of blindly picking a function to attach to what is ambiguous,
> > error with EADDRNOTAVAIL to let the user know that this function is not
> > unique, and that the user must use another unique function with an
> > address offset to get to the function they want to attach to.
> > 
> > Link:
> > https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft
> > .com/
> > 
> > Cc: stable@vger.kernel.org
> > Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
> > Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> > Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
> > Link:
> > https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kern
> > el.org/ Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > (cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
> > ---
> > 
> >  kernel/trace/trace_kprobe.c | 48 +++++++++++++++++++++++++++++++++++++
> >  1 file changed, 48 insertions(+)
> 
> Again, we need a version for 5.4.y as well before we can take this
> version.

I sent the 5.4.y patch some times ago, you can find it here: 
https://lore.kernel.org/stable/20231023113623.36423-2-flaniel@linux.microsoft.com/

With the recent batch I sent, I should have cover all the stable kernels.
In case I miss one, please indicate it to me so I can fix this problem and 
ensure all stable kernels have a corresponding patch.
 
> thanks,
> 
> greg k-h


Best regards.

Re: [PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Greg KH]

On Mon, Nov 27, 2023 at 03:41:31PM +0100, Francis Laniel wrote:
> Hi!
> 
> 
> Le vendredi 24 novembre 2023, 17:17:04 CET Greg KH a écrit :
> > On Fri, Nov 24, 2023 at 01:24:13PM +0100, Francis Laniel wrote:
> > > When a kprobe is attached to a function that's name is not unique (is
> > > static and shares the name with other functions in the kernel), the
> > > kprobe is attached to the first function it finds. This is a bug as the
> > > function that it is attaching to is not necessarily the one that the
> > > user wants to attach to.
> > > 
> > > Instead of blindly picking a function to attach to what is ambiguous,
> > > error with EADDRNOTAVAIL to let the user know that this function is not
> > > unique, and that the user must use another unique function with an
> > > address offset to get to the function they want to attach to.
> > > 
> > > Link:
> > > https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft
> > > .com/
> > > 
> > > Cc: stable@vger.kernel.org
> > > Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
> > > Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> > > Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
> > > Link:
> > > https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kern
> > > el.org/ Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > (cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
> > > ---
> > > 
> > >  kernel/trace/trace_kprobe.c | 48 +++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 48 insertions(+)
> > 
> > Again, we need a version for 5.4.y as well before we can take this
> > version.
> 
> I sent the 5.4.y patch some times ago, you can find it here: 
> https://lore.kernel.org/stable/20231023113623.36423-2-flaniel@linux.microsoft.com/
> 
> With the recent batch I sent, I should have cover all the stable kernels.
> In case I miss one, please indicate it to me so I can fix this problem and 
> ensure all stable kernels have a corresponding patch.

I only see the following in my stable mbox right now:

   1   C Nov 27 Francis Laniel  (4.4K) ┬─>[PATCH 5.10.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols
   2 r C Nov 24 Francis Laniel  (4.4K) └─>[PATCH 5.10.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols
   3   F Nov 24 To Francis Lani (1.5K)   └─>
   4 r T Nov 27 Francis Laniel  (1.9K)     └─>
   5   F Nov 27 To Francis Lani (2.0K)       └─>
  23 r C Nov 24 Francis Laniel  (2.7K) [PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols
  24 r + Nov 27 Francis Laniel  (2.0K) └─>                                                                                     

So could you resend them all just to be sure I have all of the latest versions
that you wish to have applied?

thanks,

greg "drowning in patches" k-h

[PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Francis Laniel]

When a kprobe is attached to a function that's name is not unique (is
static and shares the name with other functions in the kernel), the
kprobe is attached to the first function it finds. This is a bug as the
function that it is attaching to is not necessarily the one that the
user wants to attach to.

Instead of blindly picking a function to attach to what is ambiguous,
error with EADDRNOTAVAIL to let the user know that this function is not
unique, and that the user must use another unique function with an
address offset to get to the function they want to attach to.

Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/

Cc: stable@vger.kernel.org
Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
(cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
---
 kernel/trace/trace_kprobe.c | 48 +++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 36dfea29d5fa..720110942505 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -715,6 +715,36 @@ static inline void sanitize_event_name(char *name)
 			*name = '_';
 }
 
+struct count_symbols_struct {
+	const char *func_name;
+	unsigned int count;
+};
+
+static int count_symbols(void *data, const char *name, struct module *unused0,
+			 unsigned long unused1)
+{
+	struct count_symbols_struct *args = data;
+
+	if (strcmp(args->func_name, name))
+		return 0;
+
+	args->count++;
+
+	return 0;
+}
+
+static unsigned int number_of_same_symbols(char *func_name)
+{
+	struct count_symbols_struct args = {
+		.func_name = func_name,
+		.count = 0,
+	};
+
+	kallsyms_on_each_symbol(count_symbols, &args);
+
+	return args.count;
+}
+
 static int create_trace_kprobe(int argc, char **argv)
 {
 	/*
@@ -845,6 +875,24 @@ static int create_trace_kprobe(int argc, char **argv)
 	}
 	argc -= 2; argv += 2;
 
+	if (symbol && !strchr(symbol, ':')) {
+		unsigned int count;
+
+		count = number_of_same_symbols(symbol);
+		if (count > 1)
+			/*
+			 * Users should use ADDR to remove the ambiguity of
+			 * using KSYM only.
+			 */
+			return -EADDRNOTAVAIL;
+		else if (count == 0)
+			/*
+			 * We can return ENOENT earlier than when register the
+			 * kprobe.
+			 */
+			return -ENOENT;
+	}
+
 	/* setup a probe */
 	if (!event) {
 		/* Make a new event name */
-- 
2.34.1

Re: [PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Francis Laniel]

Hi!


Le lundi 27 novembre 2023, 16:44:22 CET Greg KH a écrit :
> On Mon, Nov 27, 2023 at 03:41:31PM +0100, Francis Laniel wrote:
> > Hi!
> > 
> > Le vendredi 24 novembre 2023, 17:17:04 CET Greg KH a écrit :
> > > On Fri, Nov 24, 2023 at 01:24:13PM +0100, Francis Laniel wrote:
> > > > When a kprobe is attached to a function that's name is not unique (is
> > > > static and shares the name with other functions in the kernel), the
> > > > kprobe is attached to the first function it finds. This is a bug as
> > > > the
> > > > function that it is attaching to is not necessarily the one that the
> > > > user wants to attach to.
> > > > 
> > > > Instead of blindly picking a function to attach to what is ambiguous,
> > > > error with EADDRNOTAVAIL to let the user know that this function is
> > > > not
> > > > unique, and that the user must use another unique function with an
> > > > address offset to get to the function they want to attach to.
> > > > 
> > > > Link:
> > > > https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.micros
> > > > oft
> > > > .com/
> > > > 
> > > > Cc: stable@vger.kernel.org
> > > > Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
> > > > Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> > > > Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
> > > > Link:
> > > > https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@k
> > > > ern
> > > > el.org/ Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > > (cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
> > > > ---
> > > > 
> > > >  kernel/trace/trace_kprobe.c | 48
> > > >  +++++++++++++++++++++++++++++++++++++
> > > >  1 file changed, 48 insertions(+)
> > > 
> > > Again, we need a version for 5.4.y as well before we can take this
> > > version.
> > 
> > I sent the 5.4.y patch some times ago, you can find it here:
> > https://lore.kernel.org/stable/20231023113623.36423-2-flaniel@linux.micros
> > oft.com/
> > 
> > With the recent batch I sent, I should have cover all the stable kernels.
> > In case I miss one, please indicate it to me so I can fix this problem and
> > ensure all stable kernels have a corresponding patch.
> 
> I only see the following in my stable mbox right now:
> 
>    1   C Nov 27 Francis Laniel  (4.4K) ┬─>[PATCH 5.10.y] tracing/kprobes:
> Return EADDRNOTAVAIL when func matches several symbols 2 r C Nov 24 Francis
> Laniel  (4.4K) └─>[PATCH 5.10.y] tracing/kprobes: Return EADDRNOTAVAIL when
> func matches several symbols 3   F Nov 24 To Francis Lani (1.5K)   └─>
>    4 r T Nov 27 Francis Laniel  (1.9K)     └─>
>    5   F Nov 27 To Francis Lani (2.0K)       └─>
>   23 r C Nov 24 Francis Laniel  (2.7K) [PATCH 4.19.y] tracing/kprobes:
> Return EADDRNOTAVAIL when func matches several symbols 24 r + Nov 27
> Francis Laniel  (2.0K) └─>
> 
> So could you resend them all just to be sure I have all of the latest
> versions that you wish to have applied?

I normally sent again the patch for version 4.14 to 5.15 (it was already 
present in 6.1 and 6.6).
I tested all of them by building the corresponding kernel with the patch 
applied before sending, so they should not break compilation or testing.

Can you please confirm me you received them?

> thanks,
> 
> greg "drowning in patches" k-h

*throws a buoy at greg k-h*


Best regards.

Re: [PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Greg KH]

On Mon, Nov 27, 2023 at 06:36:32PM +0100, Francis Laniel wrote:
> Hi!
> 
> 
> Le lundi 27 novembre 2023, 16:44:22 CET Greg KH a écrit :
> > On Mon, Nov 27, 2023 at 03:41:31PM +0100, Francis Laniel wrote:
> > > Hi!
> > > 
> > > Le vendredi 24 novembre 2023, 17:17:04 CET Greg KH a écrit :
> > > > On Fri, Nov 24, 2023 at 01:24:13PM +0100, Francis Laniel wrote:
> > > > > When a kprobe is attached to a function that's name is not unique (is
> > > > > static and shares the name with other functions in the kernel), the
> > > > > kprobe is attached to the first function it finds. This is a bug as
> > > > > the
> > > > > function that it is attaching to is not necessarily the one that the
> > > > > user wants to attach to.
> > > > > 
> > > > > Instead of blindly picking a function to attach to what is ambiguous,
> > > > > error with EADDRNOTAVAIL to let the user know that this function is
> > > > > not
> > > > > unique, and that the user must use another unique function with an
> > > > > address offset to get to the function they want to attach to.
> > > > > 
> > > > > Link:
> > > > > https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.micros
> > > > > oft
> > > > > .com/
> > > > > 
> > > > > Cc: stable@vger.kernel.org
> > > > > Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
> > > > > Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> > > > > Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
> > > > > Link:
> > > > > https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@k
> > > > > ern
> > > > > el.org/ Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > > > (cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
> > > > > ---
> > > > > 
> > > > >  kernel/trace/trace_kprobe.c | 48
> > > > >  +++++++++++++++++++++++++++++++++++++
> > > > >  1 file changed, 48 insertions(+)
> > > > 
> > > > Again, we need a version for 5.4.y as well before we can take this
> > > > version.
> > > 
> > > I sent the 5.4.y patch some times ago, you can find it here:
> > > https://lore.kernel.org/stable/20231023113623.36423-2-flaniel@linux.micros
> > > oft.com/
> > > 
> > > With the recent batch I sent, I should have cover all the stable kernels.
> > > In case I miss one, please indicate it to me so I can fix this problem and
> > > ensure all stable kernels have a corresponding patch.
> > 
> > I only see the following in my stable mbox right now:
> > 
> >    1   C Nov 27 Francis Laniel  (4.4K) ┬─>[PATCH 5.10.y] tracing/kprobes:
> > Return EADDRNOTAVAIL when func matches several symbols 2 r C Nov 24 Francis
> > Laniel  (4.4K) └─>[PATCH 5.10.y] tracing/kprobes: Return EADDRNOTAVAIL when
> > func matches several symbols 3   F Nov 24 To Francis Lani (1.5K)   └─>
> >    4 r T Nov 27 Francis Laniel  (1.9K)     └─>
> >    5   F Nov 27 To Francis Lani (2.0K)       └─>
> >   23 r C Nov 24 Francis Laniel  (2.7K) [PATCH 4.19.y] tracing/kprobes:
> > Return EADDRNOTAVAIL when func matches several symbols 24 r + Nov 27
> > Francis Laniel  (2.0K) └─>
> > 
> > So could you resend them all just to be sure I have all of the latest
> > versions that you wish to have applied?
> 
> I normally sent again the patch for version 4.14 to 5.15 (it was already 
> present in 6.1 and 6.6).
> I tested all of them by building the corresponding kernel with the patch 
> applied before sending, so they should not break compilation or testing.
> 
> Can you please confirm me you received them?

Got them now, thanks, I'll dig through them after this latest round of
stable kernels gets released.

thanks,

greg k-h

Re: [PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Francis Laniel]

Hi!


Le lundi 27 novembre 2023, 18:58:10 CET Greg KH a écrit :
> On Mon, Nov 27, 2023 at 06:36:32PM +0100, Francis Laniel wrote:
> > Hi!
> > 
> > Le lundi 27 novembre 2023, 16:44:22 CET Greg KH a écrit :
> > > On Mon, Nov 27, 2023 at 03:41:31PM +0100, Francis Laniel wrote:
> > > > Hi!
> > > > 
> > > > Le vendredi 24 novembre 2023, 17:17:04 CET Greg KH a écrit :
> > > > > On Fri, Nov 24, 2023 at 01:24:13PM +0100, Francis Laniel wrote:
> > > > > > When a kprobe is attached to a function that's name is not unique
> > > > > > (is
> > > > > > static and shares the name with other functions in the kernel),
> > > > > > the
> > > > > > kprobe is attached to the first function it finds. This is a bug
> > > > > > as
> > > > > > the
> > > > > > function that it is attaching to is not necessarily the one that
> > > > > > the
> > > > > > user wants to attach to.
> > > > > > 
> > > > > > Instead of blindly picking a function to attach to what is
> > > > > > ambiguous,
> > > > > > error with EADDRNOTAVAIL to let the user know that this function
> > > > > > is
> > > > > > not
> > > > > > unique, and that the user must use another unique function with an
> > > > > > address offset to get to the function they want to attach to.
> > > > > > 
> > > > > > Link:
> > > > > > https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.mi
> > > > > > cros
> > > > > > oft
> > > > > > .com/
> > > > > > 
> > > > > > Cc: stable@vger.kernel.org
> > > > > > Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
> > > > > > Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> > > > > > Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
> > > > > > Link:
> > > > > > https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea7
> > > > > > 42@k
> > > > > > ern
> > > > > > el.org/ Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > > > > (cherry picked from commit
> > > > > > b022f0c7e404887a7c5229788fc99eff9f9a80d5)
> > > > > > ---
> > > > > > 
> > > > > >  kernel/trace/trace_kprobe.c | 48
> > > > > >  +++++++++++++++++++++++++++++++++++++
> > > > > >  1 file changed, 48 insertions(+)
> > > > > 
> > > > > Again, we need a version for 5.4.y as well before we can take this
> > > > > version.
> > > > 
> > > > I sent the 5.4.y patch some times ago, you can find it here:
> > > > https://lore.kernel.org/stable/20231023113623.36423-2-flaniel@linux.mi
> > > > cros
> > > > oft.com/
> > > > 
> > > > With the recent batch I sent, I should have cover all the stable
> > > > kernels.
> > > > In case I miss one, please indicate it to me so I can fix this problem
> > > > and
> > > > ensure all stable kernels have a corresponding patch.
> > > 
> > > I only see the following in my stable mbox right now:
> > >    1   C Nov 27 Francis Laniel  (4.4K) ┬─>[PATCH 5.10.y] tracing/
kprobes:
> > > Return EADDRNOTAVAIL when func matches several symbols 2 r C Nov 24
> > > Francis
> > > Laniel  (4.4K) └─>[PATCH 5.10.y] tracing/kprobes: Return EADDRNOTAVAIL
> > > when
> > > func matches several symbols 3   F Nov 24 To Francis Lani (1.5K)   └─>
> > > 
> > >    4 r T Nov 27 Francis Laniel  (1.9K)     └─>
> > >    5   F Nov 27 To Francis Lani (2.0K)       └─>
> > >   
> > >   23 r C Nov 24 Francis Laniel  (2.7K) [PATCH 4.19.y] tracing/kprobes:
> > > Return EADDRNOTAVAIL when func matches several symbols 24 r + Nov 27
> > > Francis Laniel  (2.0K) └─>
> > > 
> > > So could you resend them all just to be sure I have all of the latest
> > > versions that you wish to have applied?
> > 
> > I normally sent again the patch for version 4.14 to 5.15 (it was already
> > present in 6.1 and 6.6).
> > I tested all of them by building the corresponding kernel with the patch
> > applied before sending, so they should not break compilation or testing.
> > 
> > Can you please confirm me you received them?
> 
> Got them now, thanks, I'll dig through them after this latest round of
> stable kernels gets released.

You are welcome!
Take your time, this is indeed a bug fix but not a major one (I am doubtful 
plenty of people met this).
If you find anything wrong with one of the patch, send a message and I will for 
sure polish it.

> thanks,
> 
> greg k-h


Best regards.

[PATCH 4.19.y] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

[Francis Laniel]

When a kprobe is attached to a function that's name is not unique (is
static and shares the name with other functions in the kernel), the
kprobe is attached to the first function it finds. This is a bug as the
function that it is attaching to is not necessarily the one that the
user wants to attach to.

Instead of blindly picking a function to attach to what is ambiguous,
error with EADDRNOTAVAIL to let the user know that this function is not
unique, and that the user must use another unique function with an
address offset to get to the function they want to attach to.

Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/

Cc: stable@vger.kernel.org
Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
(cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5)
---
 kernel/trace/trace_kprobe.c | 48 +++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 36dfea29d5fa..720110942505 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -715,6 +715,36 @@ static inline void sanitize_event_name(char *name)
 			*name = '_';
 }
 
+struct count_symbols_struct {
+	const char *func_name;
+	unsigned int count;
+};
+
+static int count_symbols(void *data, const char *name, struct module *unused0,
+			 unsigned long unused1)
+{
+	struct count_symbols_struct *args = data;
+
+	if (strcmp(args->func_name, name))
+		return 0;
+
+	args->count++;
+
+	return 0;
+}
+
+static unsigned int number_of_same_symbols(char *func_name)
+{
+	struct count_symbols_struct args = {
+		.func_name = func_name,
+		.count = 0,
+	};
+
+	kallsyms_on_each_symbol(count_symbols, &args);
+
+	return args.count;
+}
+
 static int create_trace_kprobe(int argc, char **argv)
 {
 	/*
@@ -845,6 +875,24 @@ static int create_trace_kprobe(int argc, char **argv)
 	}
 	argc -= 2; argv += 2;
 
+	if (symbol && !strchr(symbol, ':')) {
+		unsigned int count;
+
+		count = number_of_same_symbols(symbol);
+		if (count > 1)
+			/*
+			 * Users should use ADDR to remove the ambiguity of
+			 * using KSYM only.
+			 */
+			return -EADDRNOTAVAIL;
+		else if (count == 0)
+			/*
+			 * We can return ENOENT earlier than when register the
+			 * kprobe.
+			 */
+			return -ENOENT;
+	}
+
 	/* setup a probe */
 	if (!event) {
 		/* Make a new event name */
-- 
2.34.1