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Wed, 01 Dec 2021 12:37:08 +0000 From: mwilck@suse.com To: Christophe Varoqui , Benjamin Marzinski Date: Wed, 1 Dec 2021 13:36:43 +0100 Message-Id: <20211201123650.16240-15-mwilck@suse.com> In-Reply-To: <20211201123650.16240-1-mwilck@suse.com> References: <20211201123650.16240-1-mwilck@suse.com> MIME-Version: 1.0 X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-MIME-Autoconverted: from quoted-printable to 8bit by lists01.pubmisc.prod.ext.phx2.redhat.com id 1B1CbEAA008793 X-loop: dm-devel@redhat.com Cc: dm-devel@redhat.com, Martin Wilck Subject: [dm-devel] [PATCH v2 14/21] kpartx: open /dev/loop-control only once X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit From: Martin Wilck Opening the same file repeatedly in a loop seems wrong. For unknown reason, this patch caused gcc to diagnose a possible buffer overflow for the device name, and I had to increase the buffer by one byte. Reviewed-by: Benjamin Marzinski Signed-off-by: Martin Wilck --- kpartx/lopart.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/kpartx/lopart.c b/kpartx/lopart.c index 9b65255..2661940 100644 --- a/kpartx/lopart.c +++ b/kpartx/lopart.c @@ -159,26 +159,28 @@ char *find_loop_by_file(const char *filename) char *find_unused_loop_device(void) { - char dev[20], *next_loop_dev = NULL; + char dev[21], *next_loop_dev = NULL; int fd, next_loop = 0, somedev = 0, someloop = 0, loop_known = 0; + int next_loop_fd; struct stat statbuf; struct loop_info loopinfo; FILE *procdev; + next_loop_fd = open("/dev/loop-control", O_RDWR); + if (next_loop_fd < 0) + return NULL; + + if (!(fstat(next_loop_fd, &statbuf) == 0 && S_ISCHR(statbuf.st_mode))) { + close(next_loop_fd); + return NULL; + } + while (next_loop_dev == NULL) { - if (stat("/dev/loop-control", &statbuf) == 0 && - S_ISCHR(statbuf.st_mode)) { - int next_loop_fd; - - next_loop_fd = open("/dev/loop-control", O_RDWR); - if (next_loop_fd < 0) - return NULL; - next_loop = ioctl(next_loop_fd, LOOP_CTL_GET_FREE); + next_loop = ioctl(next_loop_fd, LOOP_CTL_GET_FREE); + if (next_loop < 0) { close(next_loop_fd); - if (next_loop < 0) - return NULL; + return NULL; } - sprintf(dev, "/dev/loop%d", next_loop); fd = open (dev, O_RDONLY); @@ -199,6 +201,9 @@ char *find_unused_loop_device(void) } break; } + + close(next_loop_fd); + if (next_loop_dev) return next_loop_dev; -- 2.33.1 -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel