[PATCH v3 00/11] Improve the copy of task comm

Yafang Shao
2024-06-21T02:30:34Z

Using {memcpy,strncpy,strcpy,kstrdup} to copy the task comm relies on the
length of task comm. Changes in the task comm could result in a destination
string that is overflow. Therefore, we should explicitly ensure the destination
string is always NUL-terminated, regardless of the task comm. This approach
will facilitate future extensions to the task comm.

As suggested by Linus [0], we can identify all relevant code with the
following git grep command:

git grep 'memcpy.*->comm\>'
git grep 'kstrdup.*->comm\>'
git grep 'strncpy.*->comm\>'
git grep 'strcpy.*->comm\>'

PATCH #2~#4: memcpy
PATCH #5~#6: kstrdup
PATCH #7~#9: strncpy
PATCH #10~#11: strcpy

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/all/CAHk-=wjAmmHUg6vho1KjzQi2=psR30+CogFd4aXrThr2gsiS4g@mail.gmail.com/ [0]

Changes:
v2->v3:
- Deduplicate code around kstrdup (Andrew)
- Add commit log for dropping task_lock (Catalin)

v1->v2: https://lore.kernel.org/bpf/20240613023044.45873-1-laoar.shao@gmail.com/
- Add comment for dropping task_lock() in __get_task_comm() (Alexei)
- Drop changes in trace event (Steven)
- Fix comment on task comm (Matus)

v1: https://lore.kernel.org/all/20240602023754.25443-1-laoar.shao@gmail.com/

Yafang Shao (11):
fs/exec: Drop task_lock() inside __get_task_comm()
auditsc: Replace memcpy() with __get_task_comm()
security: Replace memcpy() with __get_task_comm()
bpftool: Ensure task comm is always NUL-terminated
mm/util: Fix possible race condition in kstrdup()
mm/util: Deduplicate code in {kstrdup,kstrndup,kmemdup_nul}
mm/kmemleak: Replace strncpy() with __get_task_comm()
tsacct: Replace strncpy() with __get_task_comm()
tracing: Replace strncpy() with __get_task_comm()
net: Replace strcpy() with __get_task_comm()
drm: Replace strcpy() with __get_task_comm()

drivers/gpu/drm/drm_framebuffer.c | 2 +-
drivers/gpu/drm/i915/i915_gpu_error.c | 2 +-
fs/exec.c | 10 ++++++++--
include/linux/sched.h | 4 ++--
kernel/auditsc.c | 6 +++---
kernel/trace/trace.c | 2 +-
kernel/trace/trace_events_hist.c | 2 +-
kernel/tsacct.c | 2 +-
mm/internal.h | 24 ++++++++++++++++++++++++
mm/kmemleak.c | 8 +-------
mm/util.c | 21 ++++-----------------
net/ipv6/ndisc.c | 2 +-
security/lsm_audit.c | 4 ++--
security/selinux/selinuxfs.c | 2 +-
tools/bpf/bpftool/pids.c | 2 ++
15 files changed, 53 insertions(+), 40 deletions(-)

--
2.39.1