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
fce1456a19f5c08b688c29f00ef90fdfa074c79b ("knfsd: make the readahead params
cache SMP-friendly").
Cc: Greg Banks <[email protected]>
Signed-off-by: "J. Bruce Fields" <[email protected]>
Acked-by: NeilBrown <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Willy Tarreau <[email protected]>
---
fs/nfsd/vfs.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 8283236..d8b773a 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1887,7 +1887,7 @@ nfsd_racache_init(int cache_size)
raparm_hash[i].pb_head = NULL;
spin_lock_init(&raparm_hash[i].pb_lock);
}
- nperbucket = cache_size >> RAPARM_HASH_BITS;
+ nperbucket = DIV_ROUND_UP(cache_size, RAPARM_HASH_SIZE);
for (i = 0; i < cache_size - 1; i++) {
if (i % nperbucket == 0)
raparm_hash[j++].pb_head = raparml + i;
--
1.5.2.5
--
-
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