From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Max Kellermann <max.kellermann@ionos.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Sasha Levin <sashal@kernel.org>,
linux-kbuild@vger.kernel.org
Subject: [PATCH AUTOSEL 6.8 23/28] modpost: fix null pointer dereference
Date: Wed, 3 Apr 2024 13:16:25 -0400 [thread overview]
Message-ID: <20240403171656.335224-23-sashal@kernel.org> (raw)
In-Reply-To: <20240403171656.335224-1-sashal@kernel.org>
From: Max Kellermann <max.kellermann@ionos.com>
[ Upstream commit 23dfd914d2bfc4c9938b0084dffd7105de231d98 ]
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)
masahiroy@kernel.org:
The issue is reproduced with ARCH=arm allnoconfig + CONFIG_MODULES=y +
CONFIG_RUNTIME_TESTING_MENU=y + CONFIG_TEST_USER_COPY=m
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 267b9a0a3abcd..9106fe7579466 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))
--
2.43.0
parent reply other threads:[~2024-04-03 17:17 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20240403171656.335224-1-sashal@kernel.org>]
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