Messages in this thread Patch in this message | | | From | Willy Tarreau <> | Date | Wed, 22 Aug 2007 11:39:34 +0200 | Subject | [2.6.20.17 review 50/58] random: fix bound check ordering (CVE-2007-3105) |
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If root raised the default wakeup threshold over the size of the output pool, the pool transfer function could overflow the stack with RNG bytes, causing a DoS or potential privilege escalation.
(Bug reported by the PaX Team <pageexec@freemail.hu>)
Cc: Theodore Tso <tytso@mit.edu> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Willy Tarreau <w@1wt.eu> --- drivers/char/random.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c index 263e5e5..96561c8 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -693,9 +693,14 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) if (r->pull && r->entropy_count < nbytes * 8 && r->entropy_count < r->poolinfo->POOLBITS) { - int bytes = max_t(int, random_read_wakeup_thresh / 8, - min_t(int, nbytes, sizeof(tmp))); + /* If we're limited, always leave two wakeup worth's BITS */ int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4; + int bytes = nbytes; + + /* pull at least as many as BYTES as wakeup BITS */ + bytes = max_t(int, bytes, random_read_wakeup_thresh / 8); + /* but never more than the buffer size */ + bytes = min_t(int, bytes, sizeof(tmp)); DEBUG_ENT("going to reseed %s with %d bits " "(%d of %d requested) ", -- 1.5.2.5 -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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