Messages in this thread | | | From | Yafang Shao <> | Date | Thu, 14 Oct 2021 09:46:21 +0800 | Subject | Re: [PATCH v4 1/5] elfcore: use TASK_COMM_LEN instead of 16 in prpsinfo |
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On Wed, Oct 13, 2021 at 9:11 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > 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? >
Sure, I will add it. Thanks for the suggestion.
> > > > 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) >
-- Thanks Yafang
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