releases/6.8.6/modpost-fix-null-pointer-dereference.patch

   1 From da560e97a94a217794269bf19731d6a2c9340d5b Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Thu, 15 Feb 2024 15:13:21 +0100
   4 Subject: modpost: fix null pointer dereference
   5
   6 From: Max Kellermann <max.kellermann@ionos.com>
   7
   8 [ Upstream commit 23dfd914d2bfc4c9938b0084dffd7105de231d98 ]
   9
  10 If the find_fromsym() call fails and returns NULL, the warn() call
  11 will dereference this NULL pointer and cause the program to crash.
  12
  13 This happened when I tried to build with "test_user_copy" module.
  14 With this fix, it prints lots of warnings like this:
  15
  16  WARNING: modpost: lib/test_user_copy: section mismatch in reference: (unknown)+0x4 (section: .text.fixup) -> (unknown) (section: .init.text)
  17
  18 masahiroy@kernel.org:
  19  The issue is reproduced with ARCH=arm allnoconfig + CONFIG_MODULES=y +
  20  CONFIG_RUNTIME_TESTING_MENU=y + CONFIG_TEST_USER_COPY=m
  21
  22 Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
  23 Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
  24 Signed-off-by: Sasha Levin <sashal@kernel.org>
  25 ---
  26  scripts/mod/modpost.c | 4 +++-
  27  1 file changed, 3 insertions(+), 1 deletion(-)
  28
  29 diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
  30 index 6568f8177e392..ce686ebf5591f 100644
  31 --- a/scripts/mod/modpost.c
  32 +++ b/scripts/mod/modpost.c
  33 @@ -1053,7 +1053,9 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
  34         sec_mismatch_count++;
  35
  36         warn("%s: section mismatch in reference: %s+0x%x (section: %s) -> %s (section: %s)\n",
  37 -            modname, fromsym, (unsigned int)(faddr - from->st_value), fromsec, tosym, tosec);
  38 +            modname, fromsym,
  39 +            (unsigned int)(faddr - (from ? from->st_value : 0)),
  40 +            fromsec, tosym, tosec);
  41
  42         if (mismatch->mismatch == EXTABLE_TO_NON_TEXT) {
  43                 if (match(tosec, mismatch->bad_tosec))
  44 --
  45 2.43.0
  46