2024-12-10 00:17:37 +03:00
|
|
|
From 3dacd15edbed579d6966a884ce04aab95f1dfdeb Mon Sep 17 00:00:00 2001
|
2024-10-29 05:12:06 +03:00
|
|
|
From: Kees Cook <keescook@chromium.org>
|
|
|
|
Date: Mon, 22 Jan 2024 16:27:56 -0800
|
|
|
|
Subject: lib: zstd: Refactor intentional wrap-around test
|
|
|
|
|
|
|
|
In an effort to separate intentional arithmetic wrap-around from
|
|
|
|
unexpected wrap-around, we need to refactor places that depend on this
|
|
|
|
kind of math. One of the most common code patterns of this is:
|
|
|
|
|
|
|
|
VAR + value < VAR
|
|
|
|
|
|
|
|
Notably, this is considered "undefined behavior" for signed and pointer
|
|
|
|
types, which the kernel works around by using the -fno-strict-overflow
|
|
|
|
option in the build[1] (which used to just be -fwrapv). Regardless, we
|
|
|
|
want to get the kernel source to the position where we can meaningfully
|
|
|
|
instrument arithmetic wrap-around conditions and catch them when they
|
|
|
|
are unexpected, regardless of whether they are signed[2], unsigned[3],
|
|
|
|
or pointer[4] types.
|
|
|
|
|
|
|
|
Switch to a more regular type for a 64-bit value and refactor the
|
|
|
|
open-coded wrap-around addition test to use subtraction from the type max
|
|
|
|
(since add_would_overflow() may not be defined in early boot code). This
|
|
|
|
paves the way to enabling the wrap-around sanitizers in the future.
|
|
|
|
|
|
|
|
Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1]
|
|
|
|
Link: https://github.com/KSPP/linux/issues/26 [2]
|
|
|
|
Link: https://github.com/KSPP/linux/issues/27 [3]
|
|
|
|
Link: https://github.com/KSPP/linux/issues/344 [4]
|
|
|
|
Cc: Nick Terrell <terrelln@fb.com>
|
|
|
|
Cc: Paul Jones <paul@pauljones.id.au>
|
|
|
|
Cc: Sedat Dilek <sedat.dilek@gmail.com>
|
|
|
|
Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
|
|
|
|
Cc: Xin Gao <gaoxin@cdjrlc.com>
|
|
|
|
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
|
|
---
|
|
|
|
lib/zstd/decompress/zstd_decompress.c | 4 ++--
|
|
|
|
1 file changed, 2 insertions(+), 2 deletions(-)
|
|
|
|
|
|
|
|
--- a/lib/zstd/decompress/zstd_decompress.c
|
|
|
|
+++ b/lib/zstd/decompress/zstd_decompress.c
|
|
|
|
@@ -618,7 +618,7 @@ size_t ZSTD_readSkippableFrame(void* dst
|
|
|
|
* @return : decompressed size of the frames contained */
|
|
|
|
unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize)
|
|
|
|
{
|
|
|
|
- unsigned long long totalDstSize = 0;
|
|
|
|
+ U64 totalDstSize = 0;
|
|
|
|
|
|
|
|
while (srcSize >= ZSTD_startingInputLength(ZSTD_f_zstd1)) {
|
|
|
|
U32 const magicNumber = MEM_readLE32(src);
|
|
|
|
@@ -636,7 +636,7 @@ unsigned long long ZSTD_findDecompressed
|
|
|
|
{ unsigned long long const fcs = ZSTD_getFrameContentSize(src, srcSize);
|
|
|
|
if (fcs >= ZSTD_CONTENTSIZE_ERROR) return fcs;
|
|
|
|
|
|
|
|
- if (totalDstSize + fcs < totalDstSize)
|
|
|
|
+ if (U64_MAX - totalDstSize < fcs)
|
|
|
|
return ZSTD_CONTENTSIZE_ERROR; /* check for overflow */
|
|
|
|
totalDstSize += fcs;
|
|
|
|
}
|