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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7ae75637909sm255127285a.68.2024.10.07.06.25.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Oct 2024 06:25:02 -0700 (PDT) Date: Mon, 7 Oct 2024 09:25:00 -0400 From: Peter Xu To: manas18244@iiitd.ac.in Cc: Andrew Morton , Shuah Khan , Anup Sharma , linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+093d096417e7038a689b@syzkaller.appspotmail.com Subject: Re: [PATCH v4] Fixes: null pointer dereference in pfnmap_lockdep_assert Message-ID: References: <20241004-fix-null-deref-v4-1-d0a8ec01ac85@iiitd.ac.in> MIME-Version: 1.0 In-Reply-To: <20241004-fix-null-deref-v4-1-d0a8ec01ac85@iiitd.ac.in> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: 9B26140004 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: t9wew3wm36qcgsnrsk9yjbbax6swp88t X-HE-Tag: 1728307506-930156 X-HE-Meta: U2FsdGVkX18NICf9uX3QsoDRy27413oXJs4EQUI1IqyVN7hHqA19+q7e2Sb/cX05rNuqL4GOGHJOdvagTBN3x+JXAChpfH+coz5eEkeMEP4Allc5FSLeiMmeE4vO7u9zp+B3AeETtxLLDTu/bqr9WuxcGuFJlJgB20+f2gOXItT3F22rctWrRr6ew54JhjJeQBQ6NTS3laPZHA2C9+kB9+hJCQZyvl4Um+0SjEaIJYZhRQEtV7TtubyX22R8FNZxygmqi8MxBCTzx2ie+ODvBaFqkREOnJ/1YxUZag6/3kbC03WLYBLb2QSR0/LR/lzR2SMO3y6JmuSNmbBHtCHzNah+vLNnxdVgWxGH5OYfipdY+YMo/1//IUO8ujJZ2iJJ1x1oMd8cu6fVRw7aTR+CYDWXRuNBhW5VVwOsHLKz96bX2NxcUuftX/QLenx6nUh/9JG4Aw2xYQMtJ3cjhWMAaSHTNRZOsxt8Nz78NTG+DZWdyLLWn03mXVYoQ7kSKBUjCU4qHDKZl++k7MU+6uldVgSN6tzzSW9/G6YhDF9m27Y7utjWa6MjSeGIf8qe4UwsdZ+ZfjjFwpUB7a5R2zxQ/kZcQ+E6XAnk++Ak5Adh2pVlP2Lj6hTW9gqoOpvLJuskZX9stHJ+ipRUbVhl3k7o5jyofOmxAbDeHbZvDtaCyJ1E+gy+FAmelSBiFxjftXNjwgkInZ9CjvGMzAHxBDL+2unbo/9tp0D84P5EAmSQdaiJ5qM5HDjRayjb/PqufYbwYcPQamhWz6vQ/28kAJoYAI6j1DZADgRERRzkTK0JPyzp5dZmFaSzOQFx6EVR2QDPmgDOj3Fm64si0pz2lk3CIQcQwcoI51rzxwgzd1M6S2b4+PKt0oCU4pZn0UnvCGCORD8mFPv0jzXSGiqXkePSHURBxw2InRNyFPXtk3B0l9t1F2FXTV1qlCLAMGDl6toWJEs8m4JemOEL3OJZodV xPMNsney 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 04, 2024 at 11:12:16PM +0530, Manas via B4 Relay wrote: > From: Manas > > syzbot has pointed to a possible null pointer dereference in > pfnmap_lockdep_assert. vm_file member of vm_area_struct is being > dereferenced without any checks. > > This fix assigns mapping only if vm_file is not NULL. > > Reported-by: syzbot+093d096417e7038a689b@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=093d096417e7038a689b > --- > This bug[1] triggers a general protection fault in follow_pfnmap_start > function. An assertion pfnmap_lockdep_assert inside this function > dereferences vm_file member of vm_area_struct. And panic gets triggered > when vm_file is NULL. > > This patch assigns mapping only if vm_file is not NULL. > > [1] https://syzkaller.appspot.com/bug?extid=093d096417e7038a689b > > Signed-off-by: Manas Reviewed-by: Peter Xu -- Peter Xu