In an effort to separate intentional arithmetic wrap-around from unexpected wrap-around, we need to refactor places that depend on this kind of math. One of the most common code patterns of this is: VAR + value < VAR Notably, this is considered "undefined behavior" for signed and pointer types, which the kernel works around by using the -fno-strict-overflow option in the build[1] (which used to just be -fwrapv). Regardless, we want to get the kernel source to the position where we can meaningfully instrument arithmetic wrap-around conditions and catch them when they are unexpected, regardless of whether they are signed[2], unsigned[3], or pointer[4] types. Refactor open-coded wrap-around addition test to use add_would_overflow(). This paves the way to enabling the wrap-around sanitizers in the future. Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] Link: https://github.com/KSPP/linux/issues/26 [2] Link: https://github.com/KSPP/linux/issues/27 [3] Link: https://github.com/KSPP/linux/issues/344 [4] Cc: Sathya Prakash <sathya.prakash@xxxxxxxxxxxx> Cc: Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx> Cc: Suganath Prabu Subramani <suganath-prabu.subramani@xxxxxxxxxxxx> Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxx> Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx> Cc: MPT-FusionLinux.pdl@xxxxxxxxxxxx Cc: linux-scsi@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- drivers/scsi/mpt3sas/mpt3sas_ctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c b/drivers/scsi/mpt3sas/mpt3sas_ctl.c index 147cb7088d55..b36a9188720f 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c +++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c @@ -2382,7 +2382,7 @@ _ctl_diag_read_buffer(struct MPT3SAS_ADAPTER *ioc, void __user *arg) karg.bytes_to_read)); /* Truncate data on requests that are too large */ - if ((diag_data + karg.bytes_to_read < diag_data) || + if ((add_would_overflow(diag_data, karg.bytes_to_read)) || (diag_data + karg.bytes_to_read > request_data + request_size)) copy_size = request_size - karg.starting_offset; else -- 2.34.1
