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authorYafang Shao <laoar.shao@gmail.com>2022-01-19 18:08:29 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2022-01-20 08:52:53 +0200
commit95af469c4f609de011debc08e7a35b45201623a8 (patch)
tree5acdead52139bdeee5eddc9a0d73e8ba0a04520f
parent7b6397d7e5dfabf2ce1e77739d2a24af31b8a43f (diff)
fs/binfmt_elf: replace open-coded string copy with get_task_comm
It is better to use get_task_comm() instead of the open coded string copy as we do in other places. struct elf_prpsinfo is used to dump the task information in userspace coredump or kernel vmcore. Below is the verification of vmcore, crash> ps PID PPID CPU TASK ST %MEM VSZ RSS COMM 0 0 0 ffffffff9d21a940 RU 0.0 0 0 [swapper/0] > 0 0 1 ffffa09e40f85e80 RU 0.0 0 0 [swapper/1] > 0 0 2 ffffa09e40f81f80 RU 0.0 0 0 [swapper/2] > 0 0 3 ffffa09e40f83f00 RU 0.0 0 0 [swapper/3] > 0 0 4 ffffa09e40f80000 RU 0.0 0 0 [swapper/4] > 0 0 5 ffffa09e40f89f80 RU 0.0 0 0 [swapper/5] 0 0 6 ffffa09e40f8bf00 RU 0.0 0 0 [swapper/6] > 0 0 7 ffffa09e40f88000 RU 0.0 0 0 [swapper/7] > 0 0 8 ffffa09e40f8de80 RU 0.0 0 0 [swapper/8] > 0 0 9 ffffa09e40f95e80 RU 0.0 0 0 [swapper/9] > 0 0 10 ffffa09e40f91f80 RU 0.0 0 0 [swapper/10] > 0 0 11 ffffa09e40f93f00 RU 0.0 0 0 [swapper/11] > 0 0 12 ffffa09e40f90000 RU 0.0 0 0 [swapper/12] > 0 0 13 ffffa09e40f9bf00 RU 0.0 0 0 [swapper/13] > 0 0 14 ffffa09e40f98000 RU 0.0 0 0 [swapper/14] > 0 0 15 ffffa09e40f9de80 RU 0.0 0 0 [swapper/15] It works well as expected. Some comments are added to explain why we use the hard-coded 16. Link: https://lkml.kernel.org/r/20211120112738.45980-5-laoar.shao@gmail.com Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/binfmt_elf.c2
-rw-r--r--include/linux/elfcore-compat.h5
-rw-r--r--include/linux/elfcore.h5
3 files changed, 11 insertions, 1 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index f8c7f26f1fbb..b9a33cc34d6b 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1585,7 +1585,7 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid));
SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid));
rcu_read_unlock();
- strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));
+ get_task_comm(psinfo->pr_fname, p);
return 0;
}
diff --git a/include/linux/elfcore-compat.h b/include/linux/elfcore-compat.h
index e272c3d452ce..54feb64e9b5d 100644
--- a/include/linux/elfcore-compat.h
+++ b/include/linux/elfcore-compat.h
@@ -43,6 +43,11 @@ 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;
+ /*
+ * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be
+ * changed as it is exposed to userspace. We'd better make it hard-coded
+ * here.
+ */
char pr_fname[16];
char pr_psargs[ELF_PRARGSZ];
};
diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
index 957ebec35aad..746e081879a5 100644
--- a/include/linux/elfcore.h
+++ b/include/linux/elfcore.h
@@ -65,6 +65,11 @@ struct elf_prpsinfo
__kernel_gid_t pr_gid;
pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid;
/* Lots missing */
+ /*
+ * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be
+ * changed as it is exposed to userspace. We'd better make it hard-coded
+ * here.
+ */
char pr_fname[16]; /* filename of executable */
char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
};