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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48b380f04f8sm17350793f8f.9.2026.10.04.01.33.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Oct 2026 01:33:59 -0700 (PDT) Date: Sun, 4 Oct 2026 09:33:57 +0100 From: David Laight To: Michal Wilczynski Cc: Sergey Senozhatsky , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Russell King , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Minchan Kim , Jens Axboe , Andrew Morton , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-s390@vger.kernel.org, linux-block@vger.kernel.org, Yann Collet , Nick Terrell , Gao Xiang , Chao Yu , Jaegeuk Kim , Herbert Xu , Phillip Lougher , Sungguk , Jaehoon Chung , Marek Szyprowski , linux-erofs@lists.ozlabs.org, linux-f2fs-devel@lists.sourceforge.net, linux-crypto@vger.kernel.org Subject: Re: [PATCH RFC 1/9] lib/lz4: import upstream LZ4 sources verbatim Message-ID: <20261004093357.33a124b4@pumpkin> In-Reply-To: References: <20260925-lz4-vendor-upstream-v1-0-1c7ffbe21c4b@samsung.com> <20260925-lz4-vendor-upstream-v1-1-1c7ffbe21c4b@samsung.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 4 Oct 2026 01:50:39 +0200 Michal Wilczynski wrote: > On 9/28/26 07:19, Sergey Senozhatsky wrote: > > On (26/09/25 13:27), Michal Wilczynski wrote: > > [..] > >> +int LZ4_compress_fast_extState(void* state, const char* source, char* dest, int inputSize, int maxOutputSize, int acceleration) > >> +{ > >> + LZ4_stream_t_internal* const ctx = & LZ4_initStream(state, sizeof(LZ4_stream_t)) -> internal_donotuse; > >> + assert(ctx != NULL); > > > > Probably in some other places as well: > > > > LZ4_initStream() can return NULL, but the code immediately derefs > > the pointer. The assert() check seems to be misplaced, unless I'm > > missing something. > > > > I suppose those need to be decoupled. First LZ4_initStream() call and > > NULL check, then stream->internal_donotuse. > > Good catch, this assert() is a noop in the kernel (as any build without > LZ4_DEBUG), so a NULL, undersized or misaligned wrkmem oopses in > LZ4_compress_fast(), and LZ4_compress_destSize() and LZ4_resetStreamHC() > carry on with an uninitialised state. The assert() is also just a waste of code. Debugging the NULL pointer dereference is just as easy. David > > No in-tree caller hits it (all use kmalloc/vmalloc), and I listed the > alignment requirement as a behaviour change in the cover letter. Still, > the vendored files need to stay verbatim. > > So in v2 our own entry points can check alignment with a WARN_ON_ONCE() > and bail out early. It might be something that we can fix upstream as > well. > > > > > > Best regards,