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Wed, 26 Aug 2026 02:58:31 +0000 X-Mizu-Trace-ID: 61c7a6b2cb34e485 X-Migadu-Flow: FLOW_OUT Date: Wed, 26 Aug 2026 10:58:26 +0800 From: Hao Li To: Longlong Xia Cc: vbabka@kernel.org, harry@kernel.org, akpm@linux-foundation.org, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Longlong Xia Subject: Re: [PATCH v2 1/1] mm/slab_common: reject zero object_size before calculate_alignment Message-ID: References: <20260826015506.3178758-1-xialonglong2025@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260826015506.3178758-1-xialonglong2025@163.com> X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 681A4160002 X-Stat-Signature: p5zxc4jhmefsgwb3eio5wc6b48zf3nes X-HE-Tag: 1787713113-571924 X-HE-Meta: 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 2fDnlC1Q qkdJOwZc7mbFOqD7bXDIXVJIzQbD40vAZdSITj/qkNPvTrlM8tv4rVdBiQnlN9VThXctqLeG3DjzByYvygNYrGiRCoa6mBcWhDg60NBL2WoCCUjlnPGyM0XICRpe7lTRJXQIt4IPnoRhWb4cRHvXQbTKKw2QFV0uuGAR//DJnX9awQN6ziDXOGf4qwwVCTI06aDmObgKJ1kosEvM0tptoVXIm0aTRkN0ADq/lkVl8RY7/OWHQVZAH+Pt3IeuI6SYV5Y1s8lXxYJXF5anldLbFBM87RPGBkKtr/mSoFXYHc/9j+LMm0eLZRg9PlhwSd5BdzsUcFtJqLMZj+5iQenuHTepd7YbRT5ER3zQ5vedoGrBG+7s= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Aug 26, 2026 at 09:55:06AM +0800, Longlong Xia wrote: > From: Longlong Xia > > calculate_alignment() with SLAB_HWCACHE_ALIGN halves ralign in a > while (size <= ralign / 2) loop. When size is 0, ralign eventually > reaches 0 and the condition stays true indefinitely, hanging the > kernel. > > kmem_cache_sanity_check() rejected size > KMALLOC_MAX_SIZE but not > size == 0. Add !size to the check so a 0-size kmem_cache_create() is > caught on CONFIG_DEBUG_VM builds, where it can be diagnosed when it > surfaces. > > Suggested-by: Hao Li > Assisted-by: Codex:gpt-5.6-sol > Signed-off-by: Longlong Xia > --- > Changes in v2: > - Drop the !object_size check in __kmem_cache_create_args() that v1 > added to the always-compiled path, and keep the guard only in the > debug-only kmem_cache_sanity_check(), as suggested by Hao Li. > > Link: https://lore.kernel.org/all/20260824092454.1693745-1-xialonglong2025@163.com/ > --- > mm/slab_common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 95ddbab290d4..e205a99d85cf 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -102,7 +102,7 @@ static bool kmem_cache_is_duplicate_name(const char *name) > > static int kmem_cache_sanity_check(const char *name, unsigned int size) > { > - if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { > + if (!name || in_interrupt() || !size || size > KMALLOC_MAX_SIZE) { Looks good to me. thanks. Reviewed-by: Hao Li > pr_err("kmem_cache_create(%s) integrity check failed\n", name); > return -EINVAL; > } > -- > 2.43.0 >