From: Leizhen Zhang <lzsx618@gmail.com>
To: nathan@kernel.org, nsc@kernel.org
Cc: masahiroy@kernel.org, ardb@kernel.org, rostedt@goodmis.org,
hpa@zytor.com, linux-kbuild@vger.kernel.org,
linux-kernel@vger.kernel.org, Leizhen Zhang <lzsx618@gmail.com>
Subject: [PATCH v3 5/6] sorttable: avoid pointer arithmetic overflow when locating sort_needed
Date: Mon, 9 Nov 2026 18:00:02 -0600 [thread overview]
Message-ID: <20261110000003.1719966-6-lzsx618@gmail.com> (raw)
In-Reply-To: <20261110000003.1719966-1-lzsx618@gmail.com>
The location of the main_extable_sort_needed variable is computed as
(void *)ehdr + shdr_offset(sec) + sym_value(sym) - shdr_addr(sec)
which first adds the symbol's virtual address (e.g. 0xffffffff8...) to
the pointer and only then subtracts the section address. The
intermediate pointer overflows, which is undefined behaviour and is
reported by UBSan.
Subtract the section address from the symbol value first.
The problem was found with UBSan, and the analysis and fix were
prepared with the help of an AI coding assistant; I reviewed and
tested the result.
Fixes: a79f248b9b30 ("scripts: Add sortextable to sort the kernel's exception table.")
Signed-off-by: Leizhen Zhang <lzsx618@gmail.com>
---
scripts/sorttable.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 88e49a5c4251..0425e00c490f 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -788,7 +788,7 @@ static int do_sort(Elf_Ehdr *ehdr,
sort_needed_sec = get_index(shdr_start, shentsize, sort_need_index);
sort_needed_loc = (void *)ehdr +
shdr_offset(sort_needed_sec) +
- sym_value(sort_needed_sym) - shdr_addr(sort_needed_sec);
+ (sym_value(sort_needed_sym) - shdr_addr(sort_needed_sec));
/* extable has been sorted, clear the flag */
elf_parser.w(0, sort_needed_loc);
--
2.34.1
next prev parent reply other threads:[~2026-11-10 0:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-09 23:59 [PATCH v3 0/6] kbuild: fix UB hit by normal builds in host tools Leizhen Zhang
2026-11-09 23:59 ` [PATCH v3 1/6] genksyms: fix infinite loop on declarations with parameter lists Leizhen Zhang
2026-11-09 23:59 ` [PATCH v3 2/6] kallsyms: do not call qsort() with a NULL table Leizhen Zhang
2026-11-10 0:00 ` [PATCH v3 3/6] modpost: fix handling of short reads in read_text_file() Leizhen Zhang
2026-11-10 0:00 ` [PATCH v3 4/6] modpost: fix pointer arithmetic on NULL in parse_source_files() Leizhen Zhang
2026-11-10 0:00 ` Leizhen Zhang [this message]
2026-11-10 0:00 ` [PATCH v3 6/6] tools/include: fix signed shift overflow in 32-bit unaligned accessors Leizhen Zhang
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