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authorJ. Bruce Fields <bfields@citi.umich.edu>2007-07-19 01:49:18 -0700
committerWilly Tarreau <w@1wt.eu>2007-08-25 17:24:09 +0200
commit25d919bd316afa283e1d758967923fddcff83fd8 (patch)
parent50dd9072c45f64348e10ae61df948fef43430a0e (diff)
[PATCH] 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 fce1456a19f5c08b688c29f00ef90fdfa074c79b ("knfsd: make the readahead params cache SMP-friendly"). 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: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Willy Tarreau <w@1wt.eu>
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 8283236c6a0f..d8b773a786a6 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;
- 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;