linux-kernel - [PATCH v2] paride/pcd: return earlier when an error happens in pcd

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Date:   Sun, 22 Jan 2023 07:49:01 -0800
From:   Tom Rix <trix@...hat.com>
To:     tim@...erelk.net, axboe@...nel.dk, nathan@...nel.org,
        ndesaulniers@...gle.com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Tom Rix <trix@...hat.com>
Subject: [PATCH v2] paride/pcd: return earlier when an error happens in pcd_atapi()

clang static analysis reports
drivers/block/paride/pcd.c:856:36: warning: The left operand of '&'
  is a garbage value [core.UndefinedBinaryOperatorResult]
  tocentry->cdte_ctrl = buffer[5] & 0xf;
                        ~~~~~~~~~ ^

When the call to pcd_atapi() fails, buffer[] is in an unknown state,
so return early.

Signed-off-by: Tom Rix <trix@...hat.com>
---
v2: remove unused 'r' variable
---
 drivers/block/paride/pcd.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/block/paride/pcd.c b/drivers/block/paride/pcd.c
index a5ab40784119..47757ba1a09f 100644
--- a/drivers/block/paride/pcd.c
+++ b/drivers/block/paride/pcd.c
@@ -825,14 +825,14 @@ static int pcd_audio_ioctl(struct cdrom_device_info *cdi, unsigned int cmd, void
 			struct cdrom_tochdr *tochdr =
 			    (struct cdrom_tochdr *) arg;
 			char buffer[32];
-			int r;
 
-			r = pcd_atapi(cd, cmd, 12, buffer, "read toc header");
+			if (pcd_atapi(cd, cmd, 12, buffer, "read toc header"))
+				return -EIO;
 
 			tochdr->cdth_trk0 = buffer[2];
 			tochdr->cdth_trk1 = buffer[3];
 
-			return r ? -EIO : 0;
+			return 0;
 		}
 
 	case CDROMREADTOCENTRY:
@@ -845,13 +845,13 @@ static int pcd_audio_ioctl(struct cdrom_device_info *cdi, unsigned int cmd, void
 			struct cdrom_tocentry *tocentry =
 			    (struct cdrom_tocentry *) arg;
 			unsigned char buffer[32];
-			int r;
 
 			cmd[1] =
 			    (tocentry->cdte_format == CDROM_MSF ? 0x02 : 0);
 			cmd[6] = tocentry->cdte_track;
 
-			r = pcd_atapi(cd, cmd, 12, buffer, "read toc entry");
+			if (pcd_atapi(cd, cmd, 12, buffer, "read toc entry"))
+				return -EIO;
 
 			tocentry->cdte_ctrl = buffer[5] & 0xf;
 			tocentry->cdte_adr = buffer[5] >> 4;
@@ -866,7 +866,7 @@ static int pcd_audio_ioctl(struct cdrom_device_info *cdi, unsigned int cmd, void
 				    (((((buffer[8] << 8) + buffer[9]) << 8)
 				      + buffer[10]) << 8) + buffer[11];
 
-			return r ? -EIO : 0;
+			return 0;
 		}
 
 	default:
-- 
2.26.3