* [PATCHv4] perf tool: fix dereferencing NULL al->maps
@ 2024-07-22 19:18 Casey Chen
2024-07-22 20:49 ` Ian Rogers
0 siblings, 1 reply; 3+ messages in thread
From: Casey Chen @ 2024-07-22 19:18 UTC (permalink / raw)
To: linux-perf-users, linux-kernel, namhyung, irogers; +Cc: yzhong, Casey Chen
With 0dd5041c9a0e ("perf addr_location: Add init/exit/copy functions"),
when cpumode is 3 (macro PERF_RECORD_MISC_HYPERVISOR),
thread__find_map() could return with al->maps being NULL.
The path below could add a callchain_cursor_node with NULL ms.maps.
add_callchain_ip()
thread__find_symbol(.., &al)
thread__find_map(.., &al) // al->maps becomes NULL
ms.maps = maps__get(al.maps)
callchain_cursor_append(..., &ms, ...)
node->ms.maps = maps__get(ms->maps)
Then the path below would dereference NULL maps and get segfault.
fill_callchain_info()
maps__machine(node->ms.maps);
Fix it by checking if maps is NULL in fill_callchain_info().
---
tools/perf/util/callchain.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 1730b852a947..6d075648d2cc 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -1141,7 +1141,7 @@ int hist_entry__append_callchain(struct hist_entry *he, struct perf_sample *samp
int fill_callchain_info(struct addr_location *al, struct callchain_cursor_node *node,
bool hide_unresolved)
{
- struct machine *machine = maps__machine(node->ms.maps);
+ struct machine *machine = node->ms.maps ? maps__machine(node->ms.maps) : NULL;
maps__put(al->maps);
al->maps = maps__get(node->ms.maps);
--
2.45.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCHv4] perf tool: fix dereferencing NULL al->maps
2024-07-22 19:18 Casey Chen
@ 2024-07-22 20:49 ` Ian Rogers
0 siblings, 0 replies; 3+ messages in thread
From: Ian Rogers @ 2024-07-22 20:49 UTC (permalink / raw)
To: Casey Chen; +Cc: linux-perf-users, linux-kernel, namhyung, yzhong
On Mon, Jul 22, 2024 at 12:19 PM Casey Chen <cachen@purestorage.com> wrote:
>
> With 0dd5041c9a0e ("perf addr_location: Add init/exit/copy functions"),
> when cpumode is 3 (macro PERF_RECORD_MISC_HYPERVISOR),
> thread__find_map() could return with al->maps being NULL.
>
> The path below could add a callchain_cursor_node with NULL ms.maps.
>
> add_callchain_ip()
> thread__find_symbol(.., &al)
> thread__find_map(.., &al) // al->maps becomes NULL
> ms.maps = maps__get(al.maps)
> callchain_cursor_append(..., &ms, ...)
> node->ms.maps = maps__get(ms->maps)
>
> Then the path below would dereference NULL maps and get segfault.
>
> fill_callchain_info()
> maps__machine(node->ms.maps);
>
> Fix it by checking if maps is NULL in fill_callchain_info().
Thanks for doing this. Can:
Signed-off-by: Casey Chen <cachen@purestorage.com>
be assumed?
Reviewed-by: Ian Rogers <irogers@google.com>
Thanks,
Ian
> ---
> tools/perf/util/callchain.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index 1730b852a947..6d075648d2cc 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -1141,7 +1141,7 @@ int hist_entry__append_callchain(struct hist_entry *he, struct perf_sample *samp
> int fill_callchain_info(struct addr_location *al, struct callchain_cursor_node *node,
> bool hide_unresolved)
> {
> - struct machine *machine = maps__machine(node->ms.maps);
> + struct machine *machine = node->ms.maps ? maps__machine(node->ms.maps) : NULL;
>
> maps__put(al->maps);
> al->maps = maps__get(node->ms.maps);
> --
> 2.45.2
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCHv4] perf tool: fix dereferencing NULL al->maps
@ 2024-07-22 21:14 Casey Chen
0 siblings, 0 replies; 3+ messages in thread
From: Casey Chen @ 2024-07-22 21:14 UTC (permalink / raw)
To: linux-perf-users, linux-kernel, namhyung, irogers; +Cc: yzhong, Casey Chen
With 0dd5041c9a0e ("perf addr_location: Add init/exit/copy functions"),
when cpumode is 3 (macro PERF_RECORD_MISC_HYPERVISOR),
thread__find_map() could return with al->maps being NULL.
The path below could add a callchain_cursor_node with NULL ms.maps.
add_callchain_ip()
thread__find_symbol(.., &al)
thread__find_map(.., &al) // al->maps becomes NULL
ms.maps = maps__get(al.maps)
callchain_cursor_append(..., &ms, ...)
node->ms.maps = maps__get(ms->maps)
Then the path below would dereference NULL maps and get segfault.
fill_callchain_info()
maps__machine(node->ms.maps);
Fix it by checking if maps is NULL in fill_callchain_info().
---
tools/perf/util/callchain.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 1730b852a947..6d075648d2cc 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -1141,7 +1141,7 @@ int hist_entry__append_callchain(struct hist_entry *he, struct perf_sample *samp
int fill_callchain_info(struct addr_location *al, struct callchain_cursor_node *node,
bool hide_unresolved)
{
- struct machine *machine = maps__machine(node->ms.maps);
+ struct machine *machine = node->ms.maps ? maps__machine(node->ms.maps) : NULL;
maps__put(al->maps);
al->maps = maps__get(node->ms.maps);
--
2.45.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
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