-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jeff Garzik This is a particularly ugly on-failure bug, possibly security, since the lack of error handling here is covering up another class of bug: failure to handle copy_to_user() return values. The I4L API function ->readstat() returns an integer, and by looking at several existing driver implementations, it is clear that a negative return value was meant to indicate an error. Given that several drivers already return a negative value indicating an errno-style error, the current code would blindly accept that [negative] value as a valid amount of bytes read. Obvious damage ensues. Correcting ->readstat() handling to properly notice errors fixes the existing code to work correctly on error, and enables future patches to more easily indicate errors during operation. Signed-off-by: Jeff Garzik Cc: Karsten Keil Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Chris Wright --- drivers/isdn/i4l/isdn_common.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- linux-2.6.18.1.orig/drivers/isdn/i4l/isdn_common.c +++ linux-2.6.18.1/drivers/isdn/i4l/isdn_common.c @@ -1134,9 +1134,12 @@ isdn_read(struct file *file, char __user if (dev->drv[drvidx]->interface->readstat) { if (count > dev->drv[drvidx]->stavail) count = dev->drv[drvidx]->stavail; - len = dev->drv[drvidx]->interface-> - readstat(buf, count, drvidx, - isdn_minor2chan(minor)); + len = dev->drv[drvidx]->interface->readstat(buf, count, + drvidx, isdn_minor2chan(minor)); + if (len < 0) { + retval = len; + goto out; + } } else { len = 0; } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/