linux/drivers/char/random.c, branch v3.16

random: check for increase of entropy_count because of signed conversion

2014-07-19T05:42:13Z

The expression entropy_count -= ibytes << (ENTROPY_SHIFT + 3) could actually increase entropy_count if during assignment of the unsigned expression on the RHS (mind the -=) we reduce the value modulo 2^width(int) and assign it to entropy_count. Trinity found this. [ Commit modified by tytso to add an additional safety check for a negative entropy_count -- which should never happen, and to also add an additional paranoia check to prevent overly large count values to be passed into urandom_read(). ] Reported-by: Dave Jones Signed-off-by: Hannes Frederic Sowa Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org

Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

2014-06-18T00:23:14Z

Pull randomness bugfix from Ted Ts'o: "random: fix entropy accounting bug introduced in v3.15" * tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random: random: fix nasty entropy accounting bug

random: fix nasty entropy accounting bug

2014-06-16T01:04:32Z

Commit 0fb7a01af5b0 "random: simplify accounting code", introduced in v3.15, has a very nasty accounting problem when the entropy pool has has fewer bytes of entropy than the number of requested reserved bytes. In that case, "have_bytes - reserved" goes negative, and since size_t is unsigned, the expression: ibytes = min_t(size_t, ibytes, have_bytes - reserved); ... does not do the right thing. This is rather bad, because it defeats the catastrophic reseeding feature in the xfer_secondary_pool() path. It also can cause the "BUG: spinlock trylock failure on UP" for some kernel configurations when prandom_reseed() calls get_random_bytes() in the early init, since when the entropy count gets corrupted, credit_entropy_bits() erroneously believes that the nonblocking pool has been fully initialized (when in fact it is not), and so it calls prandom_reseed(true) recursively leading to the spinlock BUG. The logic is *not* the same it was originally, but in the cases where it matters, the behavior is the same, and the resulting code is hopefully easier to read and understand. Fixes: 0fb7a01af5b0 "random: simplify accounting code" Signed-off-by: Theodore Ts'o Cc: Greg Price Cc: stable@vger.kernel.org #v3.15

random: convert use of typedef ctl_table to struct ctl_table

2014-06-06T23:08:15Z

This typedef is unnecessary and should just be removed. Signed-off-by: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-3.16/core' of git://git.kernel.dk/linux-block into next

2014-06-02T16:29:34Z

Pull block core updates from Jens Axboe: "It's a big(ish) round this time, lots of development effort has gone into blk-mq in the last 3 months. Generally we're heading to where 3.16 will be a feature complete and performant blk-mq. scsi-mq is progressing nicely and will hopefully be in 3.17. A nvme port is in progress, and the Micron pci-e flash driver, mtip32xx, is converted and will be sent in with the driver pull request for 3.16. This pull request contains: - Lots of prep and support patches for scsi-mq have been integrated. All from Christoph. - API and code cleanups for blk-mq from Christoph. - Lots of good corner case and error handling cleanup fixes for blk-mq from Ming Lei. - A flew of blk-mq updates from me: * Provide strict mappings so that the driver can rely on the CPU to queue mapping. This enables optimizations in the driver. * Provided a bitmap tagging instead of percpu_ida, which never really worked well for blk-mq. percpu_ida relies on the fact that we have a lot more tags available than we really need, it fails miserably for cases where we exhaust (or are close to exhausting) the tag space. * Provide sane support for shared tag maps, as utilized by scsi-mq * Various fixes for IO timeouts. * API cleanups, and lots of perf tweaks and optimizations. - Remove 'buffer' from struct request. This is ancient code, from when requests were always virtually mapped. Kill it, to reclaim some space in struct request. From me. - Remove 'magic' from blk_plug. Since we store these on the stack and since we've never caught any actual bugs with this, lets just get rid of it. From me. - Only call part_in_flight() once for IO completion, as includes two atomic reads. Hopefully we'll get a better implementation soon, as the part IO stats are now one of the more expensive parts of doing IO on blk-mq. From me. - File migration of block code from {mm,fs}/ to block/. This includes bio.c, bio-integrity.c, bounce.c, and ioprio.c. From me, from a discussion on lkml. That should describe the meat of the pull request. Also has various little fixes and cleanups from Dave Jones, Shaohua Li, Duan Jiong, Fengguang Wu, Fabian Frederick, Randy Dunlap, Robert Elliott, and Sam Bradshaw" * 'for-3.16/core' of git://git.kernel.dk/linux-block: (100 commits) blk-mq: push IPI or local end_io decision to __blk_mq_complete_request() blk-mq: remember to start timeout handler for direct queue block: ensure that the timer is always added blk-mq: blk_mq_unregister_hctx() can be static blk-mq: make the sysfs mq/ layout reflect current mappings blk-mq: blk_mq_tag_to_rq should handle flush request block: remove dead code in scsi_ioctl:blk_verify_command blk-mq: request initialization optimizations block: add queue flag for disabling SG merging block: remove 'magic' from struct blk_plug blk-mq: remove alloc_hctx and free_hctx methods blk-mq: add file comments and update copyright notices blk-mq: remove blk_mq_alloc_request_pinned blk-mq: do not use blk_mq_alloc_request_pinned in blk_mq_map_request blk-mq: remove blk_mq_wait_for_tags blk-mq: initialize request in __blk_mq_alloc_request blk-mq: merge blk_mq_alloc_reserved_request into blk_mq_alloc_request blk-mq: add helper to insert requests from irq context blk-mq: remove stale comment for blk_mq_complete_request() blk-mq: allow non-softirq completions ...

random: fix BUG_ON caused by accounting simplification

2014-05-17T02:18:22Z

Commit ee1de406ba6eb1 ("random: simplify accounting logic") simplified things too much, in that it allows the following to trigger an overflow that results in a BUG_ON crash: dd if=/dev/urandom of=/dev/zero bs=67108707 count=1 Thanks to Peter Zihlstra for discovering the crash, and Hannes Frederic for analyizing the root cause. Signed-off-by: "Theodore Ts'o" Reported-by: Peter Zijlstra Reported-by: Hannes Frederic Sowa Cc: Greg Price

random: export add_disk_randomness

2014-04-28T15:29:55Z

This will be needed for pending changes to the scsi midlayer that now calls lower level block APIs, as well as any blk-mq driver that wants to contribute to the random pool. Signed-off-by: Christoph Hellwig Acked-by: "Theodore Ts'o" Signed-off-by: Jens Axboe

random: Add arch_has_random[_seed]()

2014-03-20T02:24:08Z

Add predicate functions for having arch_get_random[_seed]*(). The only current use is to avoid the loop in arch_random_refill() when arch_get_random_seed_long() is unavailable. Signed-off-by: H. Peter Anvin Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Signed-off-by: Theodore Ts'o

random: If we have arch_get_random_seed*(), try it before blocking

2014-03-20T02:22:06Z

If we have arch_get_random_seed*(), try to use it for emergency refill of the entropy pool before giving up and blocking on /dev/random. It may or may not work in the moment, but if it does work, it will give the user better service than blocking will. Reviewed-by: Ingo Molnar Signed-off-by: H. Peter Anvin Signed-off-by: Theodore Ts'o

random: Use arch_get_random_seed*() at init time and once a second

2014-03-20T02:22:06Z

Use arch_get_random_seed*() in two places in the Linux random driver (drivers/char/random.c): 1. During entropy pool initialization, use RDSEED in favor of RDRAND, with a fallback to the latter. Entropy exhaustion is unlikely to happen there on physical hardware as the machine is single-threaded at that point, but could happen in a virtual machine. In that case, the fallback to RDRAND will still provide more than adequate entropy pool initialization. 2. Once a second, issue RDSEED and, if successful, feed it to the entropy pool. To ensure an extra layer of security, only credit half the entropy just in case. Suggested-by: Linus Torvalds Reviewed-by: Ingo Molnar Signed-off-by: H. Peter Anvin Signed-off-by: Theodore Ts'o