nfsd: fix possible read-ahead cache and export table corruption
The value of nperbucket calculated here is too small--we should be rounding up
instead of down--with the result that the index j in the following loop can
overflow the raparm_hash array. At least in my case, the next thing in memory
turns out to be export_table, so the symptoms I see are crashes caused by the
appearance of four zeroed-out export entries in the first bucket of the hash
table of exports (which were actually entries in the readahead cache, a
pointer to which had been written to the export table in this initialization
code).
It looks like the bug was probably introduced with commit
fce1456a19
("knfsd: make the readahead params
cache SMP-friendly").
Cc: <stable@kernel.org>
Cc: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
d688abf50b
commit
a280df32db
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@ -1916,7 +1916,7 @@ nfsd_racache_init(int cache_size)
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raparm_hash[i].pb_head = NULL;
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spin_lock_init(&raparm_hash[i].pb_lock);
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}
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nperbucket = cache_size >> RAPARM_HASH_BITS;
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nperbucket = DIV_ROUND_UP(cache_size, RAPARM_HASH_SIZE);
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for (i = 0; i < cache_size - 1; i++) {
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if (i % nperbucket == 0)
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raparm_hash[j++].pb_head = raparml + i;
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