linux-stable.git/tools/lib/api/fs, branch v6.6.145

tools lib api: Fix mount_overload() snprintf truncation and toupper range

2026-07-24T14:03:17+00:00

[ Upstream commit fd1f70776add263f8ef38a87ae593c75303f1dcd ]

mount_overload() builds an environment variable name like
"PERF_SYSFS_ENVIRONMENT" from fs->name.  Two bugs:

1) snprintf() uses name_len as the buffer size instead of sizeof(upper_name).
   For fs->name = "sysfs" (len=5), the output is truncated to "PERF" (4
   chars + null), so getenv() never finds the intended variable.

2) mem_toupper() only uppercases name_len bytes, converting just the "PERF"
   prefix rather than the full string including the filesystem name portion.

Fix by using sizeof(upper_name) for snprintf and strlen(upper_name) for
mem_toupper, so the full "PERF_SYSFS_ENVIRONMENT" string is correctly
formatted and uppercased.

Reported-by: sashiko-bot 
Fixes: 73ca85ad364769ff ("tools lib api fs: Add FSTYPE__mount() method")
Cc: Jiri Olsa 
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

tools lib api: Fix filename__write_int() writing uninitialized stack data

2026-07-24T14:03:17+00:00

[ Upstream commit 438ece06185696e14c63c6113d5e2d34ec0a9680 ]

filename__write_int() formats an integer into a 64-byte buffer with
sprintf() then passes sizeof(buf) (64) as the write length.  This
writes all 64 bytes including uninitialized stack data past the
formatted string.  Most sysfs files reject the oversized write,
making the function always return -1.

Fix by capturing the sprintf() return value and using it as the
write length.

Reported-by: sashiko-bot 
Fixes: 3b00ea938653d136 ("tools lib api fs: Add sysfs__write_int function")
Cc: Kan Liang 
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

tools lib api: Fix missing null termination in filename__read_int/ull()

2026-07-24T14:03:17+00:00

[ Upstream commit 52b1f9678499b13b7aeb0186d9c6f486c043283f ]

filename__read_int() passes a stack buffer to read() using the full
sizeof(line) and then hands it to atoi() without null-terminating.
If a sysfs file fills the 64-byte buffer exactly, atoi() reads past
the array into uninitialized stack memory.

filename__read_ull_base() has the same issue with strtoull().

Fix both by reading sizeof(line) - 1 bytes and explicitly
null-terminating after a successful read.

Fixes: 3a351127cbc682c3 ("tools lib fs: Adopt filename__read_int from tools/perf/")
Reported-by: sashiko-bot 
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

tools api fs: More thread safety for global filesystem variables

2023-06-14T02:40:32+00:00

Multiple threads, such as with "perf top", may race to initialize a
file system path like hugetlbfs. The racy initialization of the path
leads to at least memory leaks. To avoid this initialize each fs for
reading the mount point path with pthread_once.

Mounting the file system may also be racy, so introduce a mutex over
the function. This does mean that the path is being accessed with and
without a mutex, which is inherently racy but hopefully benign,
especially as there are fewer callers to fs__mount.

Remove the fs__entries by directly using global variables, this was
done as no argument like the index can be passed to the init once
routine.

Issue found and tested with "perf top" and address sanitizer.

Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230609224004.180988-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

tools api fs: Dynamically allocate cgroupfs mount point cache, removing 4128 bytes from .bss

2023-05-28T13:25:25+00:00

Move the cgroupfs_cache_entry 4128 byte array out of .bss.

Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: K Prateek Nayak 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Masami Hiramatsu 
Cc: Namhyung Kim 
Cc: Paolo Bonzini 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Ross Zwisler 
Cc: Sean Christopherson 
Cc: Steven Rostedt (VMware) 
Cc: Tiezhu Yang 
Cc: Yang Jihong 
Link: https://lore.kernel.org/r/20230526183401.2326121-15-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

tools lib api fs tracing_path: Remove two unused MAX_PATH paths

2023-05-28T13:23:00+00:00

tracing_mnt was set but never written. tracing_events_path was set and
read on errors paths, but its value is exactly tracing_path with a
"/events" appended, so we can derive the value in the error
paths. There appears to have been a missing "/" when
tracing_events_path was initialized.

Signed-off-by: Ian Rogers 
Link: https://lore.kernel.org/r/20230526183401.2326121-8-irogers@google.com
Cc: K Prateek Nayak 
Cc: Ravi Bangoria 
Cc: Mark Rutland 
Cc: Ross Zwisler 
Cc: Steven Rostedt (Google) 
Cc: Sean Christopherson 
Cc: Yang Jihong 
Cc: Peter Zijlstra 
Cc: Adrian Hunter 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Masami Hiramatsu (Google) 
Cc: Namhyung Kim 
Cc: Leo Yan 
Cc: Andi Kleen 
Cc: Alexander Shishkin 
Cc: Kan Liang 
Cc: Tiezhu Yang 
Cc: Ingo Molnar 
Cc: Paolo Bonzini 
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

tools api fs: Avoid large static PATH_MAX arrays

2023-05-28T13:22:40+00:00

Change struct fs to have a pointer to a dynamically allocated array
rather than an array. This reduces the size of fs__entries from 24,768
bytes to 240 bytes. Read paths into a stack allocated array and
strdup. Fix off-by-1 fscanf %s in fs__read_mounts caught by
address sanitizer.

Signed-off-by: Ian Rogers 
Link: https://lore.kernel.org/r/20230526183401.2326121-7-irogers@google.com
Cc: K Prateek Nayak 
Cc: Ravi Bangoria 
Cc: Mark Rutland 
Cc: Ross Zwisler 
Cc: Steven Rostedt (Google) 
Cc: Sean Christopherson 
Cc: Yang Jihong 
Cc: Peter Zijlstra 
Cc: Adrian Hunter 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Masami Hiramatsu (Google) 
Cc: Namhyung Kim 
Cc: Leo Yan 
Cc: Andi Kleen 
Cc: Alexander Shishkin 
Cc: Kan Liang 
Cc: Tiezhu Yang 
Cc: Ingo Molnar 
Cc: Paolo Bonzini 
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

tracing: Always use canonical ftrace path

2023-02-18T19:34:09+00:00

The canonical location for the tracefs filesystem is at /sys/kernel/tracing.

But, from Documentation/trace/ftrace.rst:

  Before 4.1, all ftrace tracing control files were within the debugfs
  file system, which is typically located at /sys/kernel/debug/tracing.
  For backward compatibility, when mounting the debugfs file system,
  the tracefs file system will be automatically mounted at:

  /sys/kernel/debug/tracing

Many comments and Kconfig help messages in the tracing code still refer
to this older debugfs path, so let's update them to avoid confusion.

Link: https://lore.kernel.org/linux-trace-kernel/20230215223350.2658616-2-zwisler@google.com

Acked-by: Masami Hiramatsu (Google) 
Reviewed-by: Mukesh Ojha 
Signed-off-by: Ross Zwisler 
Signed-off-by: Steven Rostedt (Google)

tools lib api fs tracing_path: Add scandir alphasort

2022-11-15T13:24:09+00:00

tracing_events__opendir() allows iteration over files in
/tracing/events but with an arbitrary sort order.

Add a scandir alternative where the results are alphabetically sorted.

Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Caleb Biggers 
Cc: Jiri Olsa 
Cc: Kajol Jain 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Perry Taylor 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Rob Herring 
Cc: Sandipan Das 
Cc: Stephane Eranian 
Cc: Weilin Wang 
Cc: Xin Gao 
Cc: Xing Zhengjun 
Link: http://lore.kernel.org/lkml/20221114210723.2749751-4-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

tools api fs: Cache cgroupfs mount point

2021-02-17T18:09:08+00:00

Currently it parses the /proc file everytime it opens a file in the
cgroupfs.  Save the last result to avoid it (assuming it won't be
changed between the accesses).

Signed-off-by: Namhyung Kim 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lore.kernel.org/lkml/20201216090556.813996-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo