Willy Tarreau <[email protected]> writes: > From: Silvio Cesare <[email protected]> > > Change snprintf to scnprintf. There are generally two cases where using > snprintf causes problems. > > 1) Uses of size += snprintf(buf, SIZE - size, fmt, ...) > In this case, if snprintf would have written more characters than what the > buffer size (SIZE) is, then size will end up larger than SIZE. In later > uses of snprintf, SIZE - size will result in a negative number, leading > to problems. Note that size might already be too large by using > size = snprintf before the code reaches a case of size += snprintf. > > 2) If size is ultimately used as a length parameter for a copy back to user > space, then it will potentially allow for a buffer overflow and information > disclosure when size is greater than SIZE. When the size is used to index > the buffer directly, we can have memory corruption. This also means when > size = snprintf... is used, it may also cause problems since size may become > large. Copying to userspace is mitigated by the HARDENED_USERCOPY kernel > configuration. > > The solution to these issues is to use scnprintf which returns the number of > characters actually written to the buffer, so the size variable will never > exceed SIZE. > > Signed-off-by: Silvio Cesare <[email protected]> > Cc: Kalle Valo <[email protected]> > Cc: Dan Carpenter <[email protected]> > Cc: Kees Cook <[email protected]> > Cc: Will Deacon <[email protected]> > Cc: Greg KH <[email protected]> > Signed-off-by: Willy Tarreau <[email protected]>
I don't see any mention about which tree this should go to. Can I take this to wireless-drivers-next? -- Kalle Valo
