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author | Milan P. Gandhi <mgandhi@redhat.com> | 2016-12-24 22:02:46 +0530 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2017-01-09 23:15:02 -0500 |
commit | c7702b8c22712a06080e10f1d2dee1a133ec8809 (patch) | |
tree | 151e292f5407fd7fe7fb95d1da5724a821042b9b /drivers | |
parent | 2d1148f0f45079d25a0fa0d67e4fdb2a656d12fb (diff) | |
download | linux-c7702b8c22712a06080e10f1d2dee1a133ec8809.tar.gz linux-c7702b8c22712a06080e10f1d2dee1a133ec8809.tar.bz2 linux-c7702b8c22712a06080e10f1d2dee1a133ec8809.zip |
scsi: qla2xxx: Get mutex lock before checking optrom_state
There is a race condition with qla2xxx optrom functions where one thread
might modify optrom buffer, optrom_state while other thread is still
reading from it.
In couple of crashes, it was found that we had successfully passed the
following 'if' check where we confirm optrom_state to be
QLA_SREADING. But by the time we acquired mutex lock to proceed with
memory_read_from_buffer function, some other thread/process had already
modified that option rom buffer and optrom_state from QLA_SREADING to
QLA_SWAITING. Then we got ha->optrom_buffer 0x0 and crashed the system:
if (ha->optrom_state != QLA_SREADING)
return 0;
mutex_lock(&ha->optrom_mutex);
rval = memory_read_from_buffer(buf, count, &off, ha->optrom_buffer,
ha->optrom_region_size);
mutex_unlock(&ha->optrom_mutex);
With current optrom function we get following crash due to a race
condition:
[ 1479.466679] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 1479.466707] IP: [<ffffffff81326756>] memcpy+0x6/0x110
[...]
[ 1479.473673] Call Trace:
[ 1479.474296] [<ffffffff81225cbc>] ? memory_read_from_buffer+0x3c/0x60
[ 1479.474941] [<ffffffffa01574dc>] qla2x00_sysfs_read_optrom+0x9c/0xc0 [qla2xxx]
[ 1479.475571] [<ffffffff8127e76b>] read+0xdb/0x1f0
[ 1479.476206] [<ffffffff811fdf9e>] vfs_read+0x9e/0x170
[ 1479.476839] [<ffffffff811feb6f>] SyS_read+0x7f/0xe0
[ 1479.477466] [<ffffffff816964c9>] system_call_fastpath+0x16/0x1b
Below patch modifies qla2x00_sysfs_read_optrom,
qla2x00_sysfs_write_optrom functions to get the mutex_lock before
checking ha->optrom_state to avoid similar crashes.
The patch was applied and tested and same crashes were no longer
observed again.
Tested-by: Milan P. Gandhi <mgandhi@redhat.com>
Signed-off-by: Milan P. Gandhi <mgandhi@redhat.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/scsi/qla2xxx/qla_attr.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/drivers/scsi/qla2xxx/qla_attr.c b/drivers/scsi/qla2xxx/qla_attr.c index 47eb4d545d13..83f8527c0363 100644 --- a/drivers/scsi/qla2xxx/qla_attr.c +++ b/drivers/scsi/qla2xxx/qla_attr.c @@ -243,12 +243,15 @@ qla2x00_sysfs_read_optrom(struct file *filp, struct kobject *kobj, struct qla_hw_data *ha = vha->hw; ssize_t rval = 0; + mutex_lock(&ha->optrom_mutex); + if (ha->optrom_state != QLA_SREADING) - return 0; + goto out; - mutex_lock(&ha->optrom_mutex); rval = memory_read_from_buffer(buf, count, &off, ha->optrom_buffer, ha->optrom_region_size); + +out: mutex_unlock(&ha->optrom_mutex); return rval; @@ -263,14 +266,19 @@ qla2x00_sysfs_write_optrom(struct file *filp, struct kobject *kobj, struct device, kobj))); struct qla_hw_data *ha = vha->hw; - if (ha->optrom_state != QLA_SWRITING) + mutex_lock(&ha->optrom_mutex); + + if (ha->optrom_state != QLA_SWRITING) { + mutex_unlock(&ha->optrom_mutex); return -EINVAL; - if (off > ha->optrom_region_size) + } + if (off > ha->optrom_region_size) { + mutex_unlock(&ha->optrom_mutex); return -ERANGE; + } if (off + count > ha->optrom_region_size) count = ha->optrom_region_size - off; - mutex_lock(&ha->optrom_mutex); memcpy(&ha->optrom_buffer[off], buf, count); mutex_unlock(&ha->optrom_mutex); |