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* [PATCH] scripts/mod/modpost: fix null pointer dereference
@ 2024-02-15 14:13 Max Kellermann
  2024-02-17 12:24 ` Masahiro Yamada
  0 siblings, 1 reply; 5+ messages in thread
From: Max Kellermann @ 2024-02-15 14:13 UTC (permalink / raw)
  To: masahiroy, nathan, nicolas, linux-kbuild, linux-kernel; +Cc: Max Kellermann

If the find_fromsym() call fails and returns NULL, the warn() call
will dereference this NULL pointer and cause the program to crash.

This happened when I tried to build with "test_user_copy" module.
With this fix, it prints lots of warnings like this:

 WARNING: modpost: lib/test_user_copy: section mismatch in reference: (unknown)+0x4 (section: .text.fixup) -> (unknown) (section: .init.text)

Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
---
 scripts/mod/modpost.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index bf7c4b4b5ff4..6b37039c9e92 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1050,7 +1050,9 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
 	sec_mismatch_count++;
 
 	warn("%s: section mismatch in reference: %s+0x%x (section: %s) -> %s (section: %s)\n",
-	     modname, fromsym, (unsigned int)(faddr - from->st_value), fromsec, tosym, tosec);
+	     modname, fromsym,
+	     (unsigned int)(faddr - (from ? from->st_value : 0)),
+	     fromsec, tosym, tosec);
 
 	if (mismatch->mismatch == EXTABLE_TO_NON_TEXT) {
 		if (match(tosec, mismatch->bad_tosec))
-- 
2.39.2


^ permalink raw reply related	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-03-18 17:32 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2024-02-15 14:13 [PATCH] scripts/mod/modpost: fix null pointer dereference Max Kellermann
2024-02-17 12:24 ` Masahiro Yamada
2024-02-17 15:02   ` Max Kellermann
2024-03-12  9:51   ` Max Kellermann
2024-03-18 17:31     ` Masahiro Yamada

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