MIRRORS/linux-yocto
1
0
Fork 0
mirror of git://git.yoctoproject.org/linux-yocto.git synced 2025-10-22 23:13:01 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

tracing: Fix filter string testing

Browse Source 
The filter string testing uses strncpy_from_kernel/user_nofault() to
retrieve the string to test the filter against. The if() statement was
incorrect as it considered 0 as a fault, when it is only negative that it
faulted.

Running the following commands:

  # cd /sys/kernel/tracing
  # echo "filename.ustring ~ \"/proc*\"" > events/syscalls/sys_enter_openat/filter
  # echo 1 > events/syscalls/sys_enter_openat/enable
  # ls /proc/$$/maps
  # cat trace

Would produce nothing, but with the fix it will produce something like:

      ls-1192    [007] .....  8169.828333: sys_openat(dfd: ffffffffffffff9c, filename: 7efc18359904, flags: 80000, mode: 0)

Link: https://lore.kernel.org/all/CAEf4BzbVPQ=BjWztmEwBPRKHUwNfKBkS3kce-Rzka6zvbQeVpg@mail.gmail.com/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250417183003.505835fb@gandalf.local.home
Fixes: 77360f9bbc ("tracing: Add test for user space strings when filtering on string pointers")
Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Reported-by: Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2025-04-17 18:30:03 -04:00 committed by Steven Rostedt (Google)
parent 3b4e87e6a5
commit a8c5b0ed89
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
kernel/trace/trace_events_filter.c
View File

@ -808,7 +808,7 @@ static __always_inline char *test_string(char *str)
kstr = ubuf->buffer;
/* For safety, do not trust the string pointer */
if (!strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE))
if (strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE) < 0)
return NULL;
return kstr;
}
@ -827,7 +827,7 @@ static __always_inline char *test_ustring(char *str)
/* user space address? */
ustr = (char __user *)str;
if (!strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE))
if (strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE) < 0)
return NULL;
return kstr;