Messages in this thread Patch in this message | | | From | Yafang Shao <> | Subject | [PATCH v4 1/5] elfcore: use TASK_COMM_LEN instead of 16 in prpsinfo | Date | Wed, 13 Oct 2021 10:23:42 +0000 |
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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]; }; 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 */ }; static inline void elf_core_copy_regs(elf_gregset_t *elfregs, struct pt_regs *regs) -- 2.17.1
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