[PATCH 102/104] [SCSI] sd: Fix potential out-of-bounds access

From: Luis Henriques
Date: Mon Sep 30 2013 - 06:14:35 EST


3.5.7.22 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>

commit 984f1733fcee3fbc78d47e26c5096921c5d9946a upstream.

This patch fixes an out-of-bounds error in sd_read_cache_type(), found
by Google's AddressSanitizer tool. When the loop ends, we know that
"offset" lies beyond the end of the data in the buffer, so no Caching
mode page was found. In theory it may be present, but the buffer size
is limited to 512 bytes.

Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
drivers/scsi/sd.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 8e18431..68eb46e 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2226,14 +2226,9 @@ sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
}
}

- if (modepage == 0x3F) {
- sd_printk(KERN_ERR, sdkp, "No Caching mode page "
- "present\n");
- goto defaults;
- } else if ((buffer[offset] & 0x3f) != modepage) {
- sd_printk(KERN_ERR, sdkp, "Got wrong page\n");
- goto defaults;
- }
+ sd_printk(KERN_ERR, sdkp, "No Caching mode page found\n");
+ goto defaults;
+
Page_found:
if (modepage == 8) {
sdkp->WCE = ((buffer[offset + 2] & 0x04) != 0);
--
1.8.3.2

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