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Wed, 14 Feb 2024 18:32:36 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap2.dmz-prg2.suse.org with ESMTPSA id CN2ZJ0QHzWUcRQAAn2gu4w (envelope-from ); Wed, 14 Feb 2024 18:32:36 +0000 From: David Sterba To: linux-btrfs@vger.kernel.org Cc: David Sterba , stable@vger.kernel.org, Edward Adam Davis , syzbot+33f23b49ac24f986c9e8@syzkaller.appspotmail.com Subject: [PATCH 3/3] btrfs: dev-replace: properly validate device names Date: Wed, 14 Feb 2024 19:32:04 +0100 Message-ID: <982751e2f8e8cdf6b9e95d4c8eb3fcb22a1b2a25.1707935035.git.dsterba@suse.com> X-Mailer: git-send-email 2.42.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Authentication-Results: smtp-out1.suse.de; none X-Spam-Level: X-Spam-Score: -1.80 X-Spamd-Result: default: False [-1.80 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; BAYES_HAM(-3.00)[100.00%]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_MISSING_CHARSET(2.50)[]; FREEMAIL_ENVRCPT(0.00)[qq.com]; TAGGED_RCPT(0.00)[33f23b49ac24f986c9e8]; MIME_GOOD(-0.10)[text/plain]; REPLY(-4.00)[]; BROKEN_CONTENT_TYPE(1.50)[]; RCPT_COUNT_FIVE(0.00)[5]; NEURAL_HAM_LONG(-1.00)[-1.000]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MID_CONTAINS_FROM(1.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[qq.com:email,suse.com:email]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_CC(0.00)[suse.com,vger.kernel.org,qq.com,syzkaller.appspotmail.com]; RCVD_TLS_ALL(0.00)[]; SUSPICIOUS_RECIPS(1.50)[] X-Spam-Flag: NO There's a syzbot report that device name buffers passed to device replace are not properly checked for string termination which could lead to a read out of bounds in getname_kernel(). Add a helper that validates both source and target device name buffers. For devid as the source initialize the buffer to empty string in case something tries to read it later. This was originally analyzed and fixed in a different way by Edward Adam Davis (see links). Link: https://lore.kernel.org/linux-btrfs/000000000000d1a1d1060cc9c5e7@google.com/ Link: https://lore.kernel.org/linux-btrfs/tencent_44CA0665C9836EF9EEC80CB9E7E206DF5206@qq.com/ CC: stable@vger.kernel.org # 4.19+ CC: Edward Adam Davis Reported-and-tested-by: syzbot+33f23b49ac24f986c9e8@syzkaller.appspotmail.com Signed-off-by: David Sterba --- fs/btrfs/dev-replace.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c index 1502d664c892..79c4293ddf37 100644 --- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -725,6 +725,23 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, return ret; } +static int btrfs_check_replace_dev_names(struct btrfs_ioctl_dev_replace_args *args) +{ + if (args->start.srcdevid == 0) { + if (memchr(args->start.srcdev_name, 0, + sizeof(args->start.srcdev_name)) == NULL) + return -ENAMETOOLONG; + } else { + args->start.srcdev_name[0] = 0; + } + + if (memchr(args->start.tgtdev_name, 0, + sizeof(args->start.tgtdev_name)) == NULL) + return -ENAMETOOLONG; + + return 0; +} + int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info, struct btrfs_ioctl_dev_replace_args *args) { @@ -737,10 +754,9 @@ int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info, default: return -EINVAL; } - - if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') || - args->start.tgtdev_name[0] == '\0') - return -EINVAL; + ret = btrfs_check_replace_dev_names(args); + if (ret < 0) + return ret; ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name, args->start.srcdevid,