On Mon, 29 Jul 2024, Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
> Hello Andrew,
>
> Is it appropriate for you to apply this to the mm tree?
>
> 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.
Why are we normalizing calling double-underscore prefixed functions all
over the place? i.e. __get_task_comm().
get_task_comm() is widely used. At a glance, looks like it could be used
in many of the patches here too.
BR,
Jani.
>
> 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@xxxxxxxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/all/CAHk-=wjAmmHUg6vho1KjzQi2=psR30+CogFd4aXrThr2gsiS4g@xxxxxxxxxxxxxx/ [0]
>
> Changes:
> v3->v4:
> - Rename __kstrndup() to __kmemdup_nul() and define it inside mm/util.c
> (Matthew)
> - Remove unused local varaible (Simon)
>
> v2->v3: https://lore.kernel.org/all/20240621022959.9124-1-laoar.shao@xxxxxxxxx/
> - 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@xxxxxxxxx/
> - 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@xxxxxxxxx/
>
> 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/kmemleak.c | 8 +---
> mm/util.c | 61 ++++++++++++---------------
> net/ipv6/ndisc.c | 2 +-
> security/lsm_audit.c | 4 +-
> security/selinux/selinuxfs.c | 2 +-
> tools/bpf/bpftool/pids.c | 2 +
> 14 files changed, 51 insertions(+), 58 deletions(-)
--
Jani Nikula, Intel
