Messages in this thread Patch in this message | | | From | "J. Bruce Fields" <> | Subject | [PATCH 1/5] nfsd: fix possible read-ahead cache and export table corruption | Date | Wed, 18 Jul 2007 18:57:26 -0400 |
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From: J. Bruce Fields <bfields@citi.umich.edu>
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: stable@kernel.org Cc: Greg Banks <gnb@melbourne.sgi.com> Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu> --- 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 e90f4a8..b8da5dd 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1916,7 +1916,7 @@ 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; -- 1.5.3.rc2 - 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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