[PATCH] [SCSI] megaraid_sas: Fix possible divide-by-zero bugs in megaraid_sas_fp.c

From: Tuo Li
Date: Wed Aug 11 2021 - 09:17:23 EST


In the function mega_mod64(). the variable is checked in:
if (!divisor)

This indicates that divisor can be zero.
If so, a divide-by-zero bug will occur:
remainder = do_div(d, divisor);

Also, in the function mega_div64_32(), a divide-by-zero bug can also occur
if divisor is NULL.

To fix these divide-by-zero bugs, the functions return 0 if divisor is
zero.

Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
Signed-off-by: Tuo Li <islituo@xxxxxxxxx>
---
drivers/scsi/megaraid/megaraid_sas_fp.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_fp.c b/drivers/scsi/megaraid/megaraid_sas_fp.c
index 83f69c33b01a..05eb0d201aed 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fp.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fp.c
@@ -72,8 +72,10 @@ u32 mega_mod64(u64 dividend, u32 divisor)
u64 d;
u32 remainder;

- if (!divisor)
+ if (!divisor) {
printk(KERN_ERR "megasas : DIVISOR is zero, in div fn\n");
+ return 0;
+ }
d = dividend;
remainder = do_div(d, divisor);
return remainder;
@@ -90,8 +92,10 @@ static u64 mega_div64_32(uint64_t dividend, uint32_t divisor)
{
u64 d = dividend;

- if (!divisor)
+ if (!divisor) {
printk(KERN_ERR "megasas : DIVISOR is zero in mod fn\n");
+ return 0;
+ }

do_div(d, divisor);

--
2.25.1