Messages in this thread Patch in this message | | | Date | Wed, 13 Oct 2021 09:11:04 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH v4 1/5] elfcore: use TASK_COMM_LEN instead of 16 in prpsinfo |
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On Wed, 13 Oct 2021 10:23:42 +0000 Yafang Shao <laoar.shao@gmail.com> wrote:
> kernel test robot reported a -Wstringop-truncation warning after I > extend task comm from 16 to 24. Below is the detailed warning: > > fs/binfmt_elf.c: In function 'fill_psinfo.isra': > >> fs/binfmt_elf.c:1575:9: warning: 'strncpy' output may be truncated copying 16 bytes from a string of length 23 [-Wstringop-truncation] > 1575 | strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > This patch can fix this warning. > > struct elf_prpsinfo was moved from include/uapi/linux/elfcore.h into > include/linux/elfcore.h in commit > 1e6b57d6421f ("unexport linux/elfcore.h") > > As it is not UAPI code, we can replace 16 with TASK_COMM_LEN without > worrying about breaking userspace things. > > struct elf_prpsinfo is used to dump the task information in userspace > coredump or kernel vmcore. So I verified what will happen to vmcore if > I extend the size of TASK_COMM_LEN to 24. The result is that the vmcore > still work fine as expected, for example: > > crash> ps > PID PPID CPU TASK ST %MEM VSZ RSS COMM > > 0 0 0 ffffffff8501a940 RU 0.0 0 0 [swapper/0] > > 0 0 1 ffff996e00f81f80 RU 0.0 0 0 [swapper/1] > > 0 0 2 ffff996e00f80000 RU 0.0 0 0 [swapper/2] > > 0 0 3 ffff996e00f85e80 RU 0.0 0 0 [swapper/3] > > 0 0 4 ffff996e00f83f00 RU 0.0 0 0 [swapper/4] > 0 0 5 ffff996e00f8de80 RU 0.0 0 0 [swapper/5] > > 0 0 6 ffff996e00f8bf00 RU 0.0 0 0 [swapper/6] > > 0 0 7 ffff996e00f89f80 RU 0.0 0 0 [swapper/7] > > 0 0 8 ffff996e00f88000 RU 0.0 0 0 [swapper/8] > > 0 0 9 ffff996e00f93f00 RU 0.0 0 0 [swapper/9] > > 0 0 10 ffff996e00f91f80 RU 0.0 0 0 [swapper/10] > > 0 0 11 ffff996e00f90000 RU 0.0 0 0 [swapper/11] > > 0 0 12 ffff996e00f95e80 RU 0.0 0 0 [swapper/12] > > 0 0 13 ffff996e00f98000 RU 0.0 0 0 [swapper/13] > > 0 0 14 ffff996e00f9de80 RU 0.0 0 0 [swapper/14] > > 0 0 15 ffff996e00f9bf00 RU 0.0 0 0 [swapper/15] > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Kees Cook <keescook@chromium.org> > Cc: Al Viro <viro@zeniv.linux.org.uk> > Cc: Petr Mladek <pmladek@suse.com> > --- > include/linux/elfcore-compat.h | 2 +- > include/linux/elfcore.h | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/include/linux/elfcore-compat.h b/include/linux/elfcore-compat.h > index e272c3d452ce..8a52a782161d 100644 > --- a/include/linux/elfcore-compat.h > +++ b/include/linux/elfcore-compat.h > @@ -43,7 +43,7 @@ struct compat_elf_prpsinfo > __compat_uid_t pr_uid; > __compat_gid_t pr_gid; > compat_pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid; > - char pr_fname[16]; > + char pr_fname[TASK_COMM_LEN]; > char pr_psargs[ELF_PRARGSZ]; > };
Nice clean up, but should we add "#include <linux/sched.h>" to this header, to make sure that it pulls in TASK_COMM_LEN define and not just hope it gets pulled in beforehand by chance?
> > diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h > index 2aaa15779d50..ff4e4e455160 100644 > --- a/include/linux/elfcore.h > +++ b/include/linux/elfcore.h > @@ -65,8 +65,8 @@ struct elf_prpsinfo > __kernel_gid_t pr_gid; > pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid; > /* Lots missing */ > - char pr_fname[16]; /* filename of executable */ > - char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */ > + char pr_fname[TASK_COMM_LEN]; /* filename of executable */ > + char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
This header is fine, as it pulls in sched/task_stack.h which includes sched.h.
-- Steve
> }; > > static inline void elf_core_copy_regs(elf_gregset_t *elfregs, struct pt_regs *regs)
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