diff options
authorBrian King <brking@linux.vnet.ibm.com>2015-07-14 11:41:33 -0500
committerJames Bottomley <JBottomley@Odin.com>2015-07-30 10:38:47 -0700
commit3f1c0581310d5d94bd72740231507e763a6252a4 (patch)
parentbb7c54339e6a10ecce5c4961adf5e75b3cf0af30 (diff)
ipr: Fix invalid array indexing for HRRQ
Fixes another signed / unsigned array indexing bug in the ipr driver. Currently, when hrrq_index wraps, it becomes a negative number. We do the modulo, but still have a negative number, so we end up indexing backwards in the array. Given where the hrrq array is located in memory, we probably won't actually reference memory we don't own, but nonetheless ipr is still looking at data within struct ipr_ioa_cfg and interpreting it as struct ipr_hrr_queue data, so bad things could certainly happen. Each ipr adapter has anywhere from 1 to 16 HRRQs. By default, we use 2 on new adapters. Let's take an example: Assume ioa_cfg->hrrq_index=0x7fffffffe and ioa_cfg->hrrq_num=4: The atomic_add_return will then return -1. We mod this with 3 and get -2, add one and get -1 for an array index. On adapters which support more than a single HRRQ, we dedicate HRRQ to adapter initialization and error interrupts so that we can optimize the other queues for fast path I/O. So all normal I/O uses HRRQ 1-15. So we want to spread the I/O requests across those HRRQs. With the default module parameter settings, this bug won't hit, only when someone sets the ipr.number_of_msix parameter to a value larger than 3 is when bad things start to happen. Cc: <stable@vger.kernel.org> Tested-by: Wen Xiong <wenxiong@linux.vnet.ibm.com> Reviewed-by: Wen Xiong <wenxiong@linux.vnet.ibm.com> Reviewed-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com> Signed-off-by: Brian King <brking@linux.vnet.ibm.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: James Bottomley <JBottomley@Odin.com>
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index 7ae9cd743eb2..a9aa38903efe 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -1052,10 +1052,15 @@ static void ipr_send_blocking_cmd(struct ipr_cmnd *ipr_cmd,
static int ipr_get_hrrq_index(struct ipr_ioa_cfg *ioa_cfg)
+ unsigned int hrrq;
if (ioa_cfg->hrrq_num == 1)
- return 0;
- else
- return (atomic_add_return(1, &ioa_cfg->hrrq_index) % (ioa_cfg->hrrq_num - 1)) + 1;
+ hrrq = 0;
+ else {
+ hrrq = atomic_add_return(1, &ioa_cfg->hrrq_index);
+ hrrq = (hrrq % (ioa_cfg->hrrq_num - 1)) + 1;
+ }
+ return hrrq;