archive mirror
 help / color / mirror / Atom feed
From: Qu Wenruo <>
Subject: [PATCH] module: Add more error message for failed kernel module loading
Date: Sat, 29 Aug 2020 19:14:37 +0800	[thread overview]
Message-ID: <> (raw)

When kernel module loading failed, user space only get one of the
following error messages:
  This is the most confusing one. From corrupted ELF header to bad
  WRITE|EXEC flags check introduced by in module_enforce_rwx_sections()
  all returns this error number.

  This is for blacklisted modules. But mod doesn't do extra explain
  on this error either.

  The only error which needs no explain.

This means, if a user got "Exec format error" from modprobe, it provides
no meaningful way for the user to debug, and will take extra time
communicating to get extra info.

So this patch will add extra error messages for -ENOEXEC and -EPERM
errors, allowing user to do better debugging and reporting.

Signed-off-by: Qu Wenruo <>
 kernel/module.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 1c5cff34d9f2..9f748c6eeb48 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2096,8 +2096,12 @@ static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 	int i;
 	for (i = 0; i < hdr->e_shnum; i++) {
-		if ((sechdrs[i].sh_flags & shf_wx) == shf_wx)
+		if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) {
+			pr_err(
+			"Module %s section %d has invalid WRITE|EXEC flags\n",
+				mod->name, i);
 			return -ENOEXEC;
+		}
 	return 0;
@@ -3825,8 +3829,10 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	char *after_dashes;
 	err = elf_header_check(info);
-	if (err)
+	if (err) {
+		pr_err("Module has invalid ELF header\n");
 		goto free_copy;
+	}
 	err = setup_load_info(info, flags);
 	if (err)
@@ -3834,6 +3840,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	if (blacklisted(info->name)) {
 		err = -EPERM;
+		pr_err("Module %s is blacklisted\n", info->name);
 		goto free_copy;

             reply	other threads:[~2020-08-29 11:14 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-29 11:14 Qu Wenruo [this message]
2020-09-01 18:50 ` [PATCH] module: Add more error message for failed kernel module loading Lucas De Marchi
2020-09-01 19:56   ` Prarit Bhargava
2020-09-01 20:17     ` Lucas De Marchi
2020-09-02  0:06       ` Prarit Bhargava

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).