From 489708007785389941a89fa06aedc5ec53303c96 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 26 Feb 2006 08:34:10 -0600 Subject: [PATCH] [PATCH] sd: fix memory corruption with broken mode page headers There's a problem in sd where we blindly believe the length of the headers and block descriptors. Some devices return insane values for these and cause our length to end up greater than the actual buffer size, so check to make sure. Signed-off-by: Al Viro Also removed the buffer size magic number (512) and added DPOFUA of zero to the defaults Signed-off-by: James Bottomley Signed-off-by: Linus Torvalds --- drivers/scsi/sd.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 930db398d1..9d9872347f 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -89,6 +89,11 @@ #define SD_MAX_RETRIES 5 #define SD_PASSTHROUGH_RETRIES 1 +/* + * Size of the initial data buffer for mode and read capacity data + */ +#define SD_BUF_SIZE 512 + static void scsi_disk_release(struct kref *kref); struct scsi_disk { @@ -1239,7 +1244,7 @@ sd_do_mode_sense(struct scsi_device *sdp, int dbd, int modepage, /* * read write protect setting, if possible - called only in sd_revalidate_disk() - * called with buffer of length 512 + * called with buffer of length SD_BUF_SIZE */ static void sd_read_write_protect_flag(struct scsi_disk *sdkp, char *diskname, @@ -1297,7 +1302,7 @@ sd_read_write_protect_flag(struct scsi_disk *sdkp, char *diskname, /* * sd_read_cache_type - called only from sd_revalidate_disk() - * called with buffer of length 512 + * called with buffer of length SD_BUF_SIZE */ static void sd_read_cache_type(struct scsi_disk *sdkp, char *diskname, @@ -1342,6 +1347,8 @@ sd_read_cache_type(struct scsi_disk *sdkp, char *diskname, /* Take headers and block descriptors into account */ len += data.header_length + data.block_descriptor_length; + if (len > SD_BUF_SIZE) + goto bad_sense; /* Get the data */ res = sd_do_mode_sense(sdp, dbd, modepage, buffer, len, &data, &sshdr); @@ -1354,6 +1361,12 @@ sd_read_cache_type(struct scsi_disk *sdkp, char *diskname, int ct = 0; int offset = data.header_length + data.block_descriptor_length; + if (offset >= SD_BUF_SIZE - 2) { + printk(KERN_ERR "%s: malformed MODE SENSE response", + diskname); + goto defaults; + } + if ((buffer[offset] & 0x3f) != modepage) { printk(KERN_ERR "%s: got wrong page\n", diskname); goto defaults; @@ -1398,6 +1411,7 @@ defaults: diskname); sdkp->WCE = 0; sdkp->RCD = 0; + sdkp->DPOFUA = 0; } /** @@ -1421,7 +1435,7 @@ static int sd_revalidate_disk(struct gendisk *disk) if (!scsi_device_online(sdp)) goto out; - buffer = kmalloc(512, GFP_KERNEL | __GFP_DMA); + buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL | __GFP_DMA); if (!buffer) { printk(KERN_WARNING "(sd_revalidate_disk:) Memory allocation " "failure.\n"); -- 2.39.5