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rtla: Ensure null termination after read operations in utils.c

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Add explicit null termination and buffer initialization for read()
operations in procfs_is_workload_pid() and get_self_cgroup() functions.
The read() system call does not null-terminate the data it reads, and
when the buffer is filled to capacity, subsequent string operations
will read past the buffer boundary searching for a null terminator.

In procfs_is_workload_pid(), explicitly set buffer[MAX_PATH-1] to '\0'
to ensure the buffer is always null-terminated before passing it to
strncmp(). In get_self_cgroup(), use memset() to zero the path buffer
before reading, which ensures null termination when retval is less than
MAX_PATH. Additionally, set path[MAX_PATH-1] to '\0' after the read to
handle the case where the buffer is filled completely.

These defensive buffer handling practices prevent potential buffer
overruns and align with the ongoing buffer safety improvements across
the rtla codebase.

Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Link: https://lore.kernel.org/r/20260106133655.249887-17-wander@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
This commit is contained in:
Wander Lairson Costa 2026-01-06 08:49:52 -03:00 committed by Tomas Glozar
parent af2962d68b
commit 33e3c807ab
1 changed files with 3 additions and 0 deletions
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3
tools/tracing/rtla/src/utils.c
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@ -317,6 +317,7 @@ static int procfs_is_workload_pid(const char *comm_prefix, struct dirent *proc_e
if (retval <= 0)
return 0;
buffer[MAX_PATH-1] = '\0';
retval = strncmp(comm_prefix, buffer, strlen(comm_prefix));
if (retval)
return 0;
@ -750,6 +751,7 @@ static int get_self_cgroup(char *self_cg, int sizeof_self_cg)
if (fd < 0)
return 0;
memset(path, 0, sizeof(path));
retval = read(fd, path, MAX_PATH);
close(fd);
@ -757,6 +759,7 @@ static int get_self_cgroup(char *self_cg, int sizeof_self_cg)
if (retval <= 0)
return 0;
path[MAX_PATH-1] = '\0';
start = path;
start = strstr(start, ":");