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eab40cf336
When under memory-pressure it is possible that the mempool which backs
the 'struct request_queue' will make use of up to BLKDEV_MIN_RQ count
emergency buffers - in case it can't get a regular allocation. These
buffers are preallocated and once they are also used, they are
re-supplied with old finished requests from the same request_queue (see
mempool_free()).
The bug is, when re-supplying the emergency pool, the old requests are
not again ran through the callback mempool_t->alloc(), and thus also not
through the callback bsg_init_rq(). Thus we skip initialization, and
while the sense-buffer still should be good, scsi_request->cmd might
have become to be an invalid pointer in the meantime. When the request
is initialized in bsg.c, and the user's CDB is larger than BLK_MAX_CDB,
bsg will replace it with a custom allocated buffer, which is freed when
the user's command is finished, thus it dangles afterwards. When next a
command is sent by the user that has a smaller/similar CDB as
BLK_MAX_CDB, bsg will assume that scsi_request->cmd is backed by
scsi_request->__cmd, will not make a custom allocation, and write into
undefined memory.
Fix this by splitting bsg_init_rq() into two functions:
- bsg_init_rq() is changed to only do the allocation of the
sense-buffer, which is used to back the bsg job's reply buffer. This
pointer should never change during the lifetime of a scsi_request, so
it doesn't need re-initialization.
- bsg_initialize_rq() is a new function that makes use of
'struct request_queue's initialize_rq_fn callback (which was
introduced in v4.12). This is always called before the request is
given out via blk_get_request(). This function does the remaining
initialization that was previously done in bsg_init_rq(), and will
also do it when the request is taken from the emergency-pool of the
backing mempool.
Fixes:
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|---|---|---|
| .. | ||
| partitions | ||
| badblocks.c | ||
| bfq-cgroup.c | ||
| bfq-iosched.c | ||
| bfq-iosched.h | ||
| bfq-wf2q.c | ||
| bio-integrity.c | ||
| bio.c | ||
| blk-cgroup.c | ||
| blk-core.c | ||
| blk-exec.c | ||
| blk-flush.c | ||
| blk-integrity.c | ||
| blk-ioc.c | ||
| blk-lib.c | ||
| blk-map.c | ||
| blk-merge.c | ||
| blk-mq-cpumap.c | ||
| blk-mq-debugfs.c | ||
| blk-mq-debugfs.h | ||
| blk-mq-pci.c | ||
| blk-mq-rdma.c | ||
| blk-mq-sched.c | ||
| blk-mq-sched.h | ||
| blk-mq-sysfs.c | ||
| blk-mq-tag.c | ||
| blk-mq-tag.h | ||
| blk-mq-virtio.c | ||
| blk-mq.c | ||
| blk-mq.h | ||
| blk-settings.c | ||
| blk-softirq.c | ||
| blk-stat.c | ||
| blk-stat.h | ||
| blk-sysfs.c | ||
| blk-tag.c | ||
| blk-throttle.c | ||
| blk-timeout.c | ||
| blk-wbt.c | ||
| blk-wbt.h | ||
| blk-zoned.c | ||
| blk.h | ||
| bounce.c | ||
| bsg-lib.c | ||
| bsg.c | ||
| cfq-iosched.c | ||
| cmdline-parser.c | ||
| compat_ioctl.c | ||
| deadline-iosched.c | ||
| elevator.c | ||
| genhd.c | ||
| ioctl.c | ||
| ioprio.c | ||
| Kconfig | ||
| Kconfig.iosched | ||
| kyber-iosched.c | ||
| Makefile | ||
| mq-deadline.c | ||
| noop-iosched.c | ||
| opal_proto.h | ||
| partition-generic.c | ||
| scsi_ioctl.c | ||
| sed-opal.c | ||
| t10-pi.c | ||