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Tue, 23 Jul 2024 21:47:13 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Eo2tGuEkoGY+QAAAD6G6ig (envelope-from ); Tue, 23 Jul 2024 21:47:13 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id A56B7A08C6; Tue, 23 Jul 2024 14:57:10 +0200 (CEST) Date: Tue, 23 Jul 2024 14:57:10 +0200 From: Jan Kara To: David Howells Cc: Alexander Viro , Christian Brauner , Jan Kara , Jeff Layton , Gao Xiang , Matthew Wilcox , netfs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] vfs: Fix potential circular locking through setxattr() and removexattr() Message-ID: <20240723125710.mtnfaycuvdi4dpdy@quack3> References: <2136178.1721725194@warthog.procyon.org.uk> Precedence: bulk X-Mailing-List: netfs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2136178.1721725194@warthog.procyon.org.uk> X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Action: no action X-Rspamd-Queue-Id: 8753C21AF9 X-Spam-Score: -3.81 X-Spam-Level: X-Spam-Flag: NO X-Spamd-Result: default: False [-3.81 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_SEVEN(0.00)[11]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.com:email]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCVD_TLS_LAST(0.00)[]; DKIM_TRACE(0.00)[suse.cz:+] Regarding the contents of the change itself: On Tue 23-07-24 09:59:54, David Howells wrote: > @@ -954,15 +952,23 @@ SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname, > SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) > { > struct fd f = fdget(fd); > + char kname[XATTR_NAME_MAX + 1]; > int error = -EBADF; > > if (!f.file) > return error; > audit_file(f.file); > + > + error = strncpy_from_user(kname, name, sizeof(kname)); > + if (error == 0 || error == sizeof(kname)) > + error = -ERANGE; > + if (error < 0) > + return error; Missing fdput() here. > + > error = mnt_want_write_file(f.file); > if (!error) { > error = removexattr(file_mnt_idmap(f.file), > - f.file->f_path.dentry, name); > + f.file->f_path.dentry, kname); > mnt_drop_write_file(f.file); > } > fdput(f); Otherwise the patch looks good to me. Honza -- Jan Kara SUSE Labs, CR