strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
In every other location psinfo->pr_fname is used, it's with strscpy_pad.
It's clear that this field needs to be NUL-terminated and potentially
NUL-padded as well.
binfmt_elf.c +1545:
| char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
| {
| task_lock(tsk);
| /* Always NUL terminated and zero-padded */
| strscpy_pad(buf, tsk->comm, buf_size);
| task_unlock(tsk);
| return buf;
| }
Note that this patch relies on the _new_ 2-argument versions of
strscpy() and strscpy_pad() introduced in Commit e6584c3964f2f ("string:
Allow 2-argument strscpy()").
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@xxxxxxxxxxxxxxx
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
Note: build-tested only.
Found with: $ rg "strncpy\("
---
fs/binfmt_elf_fdpic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 1920ed69279b..0365f14f18fc 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1359,7 +1359,7 @@ 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));
+ strscpy_pad(psinfo->pr_fname, p->comm);
return 0;
}
---
base-commit: a4145ce1e7bc247fd6f2846e8699473448717b37
change-id: 20240320-strncpy-fs-binfmt_elf_fdpic-c-828286d76310
Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>
