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Wed, 29 Jul 2026 10:42:43 -0700 (PDT) From: Laxman Acharya Padhya To: Andrew Morton Cc: Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] lib/bug: ignore non-allocated module bug tables Date: Wed, 29 Jul 2026 23:27:34 +0545 Message-ID: <20260729174234.86242-1-acharyalaxman8848@gmail.com> X-Mailer: git-send-email 2.51.2 Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit rewrite_section_headers() initially sets sh_addr for every section to its address in the temporary module image. Only SHF_ALLOC sections are later copied to module memory and have sh_addr updated. module_bug_finalize() accepts any section named __bug_table. A malformed module can therefore leave mod->bug_table pointing into the temporary image, which is freed after loading. A later BUG/WARN lookup would then scan freed memory. Require the bug table section to be allocated before retaining its address. Valid modules are unchanged because __bug_table is allocated. Fixes: 7664c5a1da47 ("[PATCH] Generic BUG implementation") Signed-off-by: Laxman Acharya Padhya --- lib/bug.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/bug.c b/lib/bug.c index 7c1c2c27f..44966ead1 100644 --- a/lib/bug.c +++ b/lib/bug.c @@ -94,7 +94,8 @@ void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, /* Find the __bug_table section, if present */ secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; for (i = 1; i < hdr->e_shnum; i++) { - if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table")) + if (strcmp(secstrings + sechdrs[i].sh_name, "__bug_table") || + !(sechdrs[i].sh_flags & SHF_ALLOC)) continue; mod->bug_table = (void *) sechdrs[i].sh_addr; mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry); -- 2.51.2