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b=cAd4B67Em+JJDgKcyZfqfbJsIn6GwDz4NX21pCWwKw3XPI1UNx1sxeWE+UXws8/Xi 4pH67x6cv7ZhXGsqXFdDIThIyN7gLW6dx3XFjTsl4BKllpD2ONXKnwK/iz4W7eTX+n FrfB8aDnaetxKdZ/XtrEFyq0CbTazRLtuvXcfeqf0UyIzrPLoFpzku3cQdqIjHNOUN HJpBv2aKjMVSRy4hgojh5oZ1aOGvXWZmOevAe4iphMxM/JtwYhf2sj4LmlqbMdC74F nOrfURh7iKZOIne/h1YuMxfmN5ePHGckgEOWNU+GFrxf4UkuBQxScgd0cVzdNyx8lU V4wOOn7KexChg== Date: Wed, 22 Apr 2026 14:44:11 +0200 From: Christian Brauner To: lirongqing Cc: Alexander Viro , Jan Kara , Kees Cook , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] fs/coredump: reduce redundant log noise in validate_coredump_safety Message-ID: <20260422-naschen-einbog-ed4f52ea472a@brauner> References: <20260410080918.2319-1-lirongqing@baidu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260410080918.2319-1-lirongqing@baidu.com> X-Stat-Signature: kbq8dtbs5xxja3g9h7zf5rszuyz3qyxc X-Rspam-User: X-Rspamd-Queue-Id: 703A820003 X-Rspamd-Server: rspam05 X-HE-Tag: 1776861856-369852 X-HE-Meta: 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 EvwVMzvA 4Fe2TdAELgRHOqV+9xg2IVhc+MtM9chGLCRk4oAoLkkHqt3OFQCUpD+48Z3EgtSo5T94wNDqQaB73/vxqNZCkUqoo7DfdHs2yxSpuu+U86cte23j85Slh+jnpFFYCgrUIY2m33Rnn6kFIIdroWGOP7sKul/kGI2coDCylN5iHmpQbZh4qCpMUlhcv+zkp+f7BjBsph0Lc1Y5UtYhwQG9JohuqSDWYiLM6V5wJXSsQ1I3sncB+LfPfKb7BimdWpFlDvoNiZDpaBWD7uqxbD2uwgKWiwEf5xR7tNljU+TB28CaOOAY5zpK1XY6LGdUPBdUM+FPePgmq0olus0CHegaQoIDbMUVHeUpN8blHMVLFYLTJ2H6lUe4Wvq8Hmw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 10, 2026 at 04:09:18AM -0400, lirongqing wrote: > From: Li RongQing > > Currently, writing to 'core_pattern' or 'suid_dumpable' sysctl nodes > always triggers validate_coredump_safety(), even if the values have > not changed. This results in redundant warning messages in dmesg: > > "Unsafe core_pattern used with fs.suid_dumpable=2..." > > This patch optimizes the procfs handlers to only invoke the safety > validation when an actual change in the configuration is detected: > > 1. In proc_dostring_coredump(), compare the new core_pattern string > with the existing one using strncmp(). > 2. In proc_dointvec_minmax_coredump(), check if the new suid_dumpable > value differs from the previous one. > > This keeps the kernel log clean from repetitive warnings when > re-applying the same sysctl settings. > > Signed-off-by: Li RongQing > --- That warning should very much serve as a reminder to not use that completely unsafe pattern. So no, move to newer coredump infra or use absolute paths, please.