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[PATCH] cdrom_sysctl_info fix
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Fix the cdrom_sysctl_info possible buffer overwrite bug. Also
fix the locking of accessing topCdromPtr pointer.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Dave Young authored and Jens Axboe committed Jul 10, 2007
1 parent 32eef96 commit 554988d
Showing 1 changed file with 125 additions and 91 deletions.
216 changes: 125 additions & 91 deletions drivers/cdrom/cdrom.c
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Original file line number Diff line number Diff line change
Expand Up @@ -302,7 +302,7 @@ module_param(lockdoor, bool, 0);
module_param(check_media_type, bool, 0);
module_param(mrw_format_restart, bool, 0);

static DEFINE_SPINLOCK(cdrom_lock);
static DEFINE_MUTEX(cdrom_mutex);

static const char *mrw_format_status[] = {
"not mrw",
Expand Down Expand Up @@ -438,10 +438,10 @@ int register_cdrom(struct cdrom_device_info *cdi)
cdo->generic_packet = cdrom_dummy_generic_packet;

cdinfo(CD_REG_UNREG, "drive \"/dev/%s\" registered\n", cdi->name);
spin_lock(&cdrom_lock);
mutex_lock(&cdrom_mutex);
cdi->next = topCdromPtr;
topCdromPtr = cdi;
spin_unlock(&cdrom_lock);
mutex_unlock(&cdrom_mutex);
return 0;
}
#undef ENSURE
Expand All @@ -452,23 +452,23 @@ int unregister_cdrom(struct cdrom_device_info *unreg)
cdinfo(CD_OPEN, "entering unregister_cdrom\n");

prev = NULL;
spin_lock(&cdrom_lock);
mutex_lock(&cdrom_mutex);
cdi = topCdromPtr;
while (cdi && cdi != unreg) {
prev = cdi;
cdi = cdi->next;
}

if (cdi == NULL) {
spin_unlock(&cdrom_lock);
mutex_unlock(&cdrom_mutex);
return -2;
}
if (prev)
prev->next = cdi->next;
else
topCdromPtr = cdi->next;

spin_unlock(&cdrom_lock);
mutex_unlock(&cdrom_mutex);

if (cdi->exit)
cdi->exit(cdi);
Expand Down Expand Up @@ -3289,103 +3289,137 @@ static struct cdrom_sysctl_settings {
int check; /* check media type */
} cdrom_sysctl_settings;

enum cdrom_print_option {
CTL_NAME,
CTL_SPEED,
CTL_SLOTS,
CTL_CAPABILITY
};

static int cdrom_print_info(const char *header, int val, char *info,
int *pos, enum cdrom_print_option option)
{
const int max_size = sizeof(cdrom_sysctl_settings.info);
struct cdrom_device_info *cdi;
int ret;

ret = scnprintf(info + *pos, max_size - *pos, header);
if (!ret)
return 1;

*pos += ret;

for (cdi = topCdromPtr; cdi; cdi = cdi->next) {
switch (option) {
case CTL_NAME:
ret = scnprintf(info + *pos, max_size - *pos,
"\t%s", cdi->name);
break;
case CTL_SPEED:
ret = scnprintf(info + *pos, max_size - *pos,
"\t%d", cdi->speed);
break;
case CTL_SLOTS:
ret = scnprintf(info + *pos, max_size - *pos,
"\t%d", cdi->capacity);
break;
case CTL_CAPABILITY:
ret = scnprintf(info + *pos, max_size - *pos,
"\t%d", CDROM_CAN(val) != 0);
break;
default:
printk(KERN_INFO "cdrom: invalid option%d\n", option);
return 1;
}
if (!ret)
return 1;
*pos += ret;
}

return 0;
}

static int cdrom_sysctl_info(ctl_table *ctl, int write, struct file * filp,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
int pos;
struct cdrom_device_info *cdi;
int pos;
char *info = cdrom_sysctl_settings.info;
const int max_size = sizeof(cdrom_sysctl_settings.info);

if (!*lenp || (*ppos && !write)) {
*lenp = 0;
return 0;
}

mutex_lock(&cdrom_mutex);

pos = sprintf(info, "CD-ROM information, " VERSION "\n");

pos += sprintf(info+pos, "\ndrive name:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%s", cdi->name);

pos += sprintf(info+pos, "\ndrive speed:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", cdi->speed);

pos += sprintf(info+pos, "\ndrive # of slots:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", cdi->capacity);

pos += sprintf(info+pos, "\nCan close tray:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_CLOSE_TRAY) != 0);

pos += sprintf(info+pos, "\nCan open tray:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_OPEN_TRAY) != 0);

pos += sprintf(info+pos, "\nCan lock tray:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_LOCK) != 0);

pos += sprintf(info+pos, "\nCan change speed:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_SELECT_SPEED) != 0);

pos += sprintf(info+pos, "\nCan select disk:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_SELECT_DISC) != 0);

pos += sprintf(info+pos, "\nCan read multisession:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_MULTI_SESSION) != 0);

pos += sprintf(info+pos, "\nCan read MCN:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_MCN) != 0);

pos += sprintf(info+pos, "\nReports media changed:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_MEDIA_CHANGED) != 0);

pos += sprintf(info+pos, "\nCan play audio:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_PLAY_AUDIO) != 0);

pos += sprintf(info+pos, "\nCan write CD-R:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_CD_R) != 0);

pos += sprintf(info+pos, "\nCan write CD-RW:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_CD_RW) != 0);

pos += sprintf(info+pos, "\nCan read DVD:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_DVD) != 0);

pos += sprintf(info+pos, "\nCan write DVD-R:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_DVD_R) != 0);

pos += sprintf(info+pos, "\nCan write DVD-RAM:");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_DVD_RAM) != 0);

pos += sprintf(info+pos, "\nCan read MRW:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_MRW) != 0);

pos += sprintf(info+pos, "\nCan write MRW:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_MRW_W) != 0);

pos += sprintf(info+pos, "\nCan write RAM:\t");
for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_RAM) != 0);

strcpy(info+pos,"\n\n");

return proc_dostring(ctl, write, filp, buffer, lenp, ppos);
if (cdrom_print_info("\ndrive name:\t", 0, info, &pos, CTL_NAME))
goto done;
if (cdrom_print_info("\ndrive speed:\t", 0, info, &pos, CTL_SPEED))
goto done;
if (cdrom_print_info("\ndrive # of slots:", 0, info, &pos, CTL_SLOTS))
goto done;
if (cdrom_print_info("\nCan close tray:\t",
CDC_CLOSE_TRAY, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan open tray:\t",
CDC_OPEN_TRAY, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan lock tray:\t",
CDC_LOCK, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan change speed:",
CDC_SELECT_SPEED, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan select disk:",
CDC_SELECT_DISC, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan read multisession:",
CDC_MULTI_SESSION, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan read MCN:\t",
CDC_MCN, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nReports media changed:",
CDC_MEDIA_CHANGED, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan play audio:\t",
CDC_PLAY_AUDIO, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan write CD-R:\t",
CDC_CD_R, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan write CD-RW:",
CDC_CD_RW, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan read DVD:\t",
CDC_DVD, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan write DVD-R:",
CDC_DVD_R, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan write DVD-RAM:",
CDC_DVD_RAM, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan read MRW:\t",
CDC_MRW, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan write MRW:\t",
CDC_MRW_W, info, &pos, CTL_CAPABILITY))
goto done;
if (cdrom_print_info("\nCan write RAM:\t",
CDC_RAM, info, &pos, CTL_CAPABILITY))
goto done;
if (!scnprintf(info + pos, max_size - pos, "\n\n"))
goto done;
doit:
mutex_unlock(&cdrom_mutex);
return proc_dostring(ctl, write, filp, buffer, lenp, ppos);
done:
printk(KERN_INFO "cdrom: info buffer too small\n");
goto doit;
}

/* Unfortunately, per device settings are not implemented through
Expand Down

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