From: Matthew Wilcox (Oracle) willy@infradead.org
commit 430f24f94c8a174d411a550d7b5529301922e67a upstream.
If there is an entry at ULONG_MAX, xa_for_each() will overflow the 'index + 1' in xa_find_after() and wrap around to 0. Catch this case and terminate the loop by returning NULL.
Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- lib/test_xarray.c | 17 +++++++++++++++++ lib/xarray.c | 3 +++ 2 files changed, 20 insertions(+)
--- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -1046,11 +1046,28 @@ static noinline void check_find_3(struct xa_destroy(xa); }
+static noinline void check_find_4(struct xarray *xa) +{ + unsigned long index = 0; + void *entry; + + xa_store_index(xa, ULONG_MAX, GFP_KERNEL); + + entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT); + XA_BUG_ON(xa, entry != xa_mk_index(ULONG_MAX)); + + entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT); + XA_BUG_ON(xa, entry); + + xa_erase_index(xa, ULONG_MAX); +} + static noinline void check_find(struct xarray *xa) { check_find_1(xa); check_find_2(xa); check_find_3(xa); + check_find_4(xa); check_multi_find(xa); check_multi_find_2(xa); } --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1847,6 +1847,9 @@ void *xa_find_after(struct xarray *xa, u XA_STATE(xas, xa, *indexp + 1); void *entry;
+ if (xas.xa_index == 0) + return NULL; + rcu_read_lock(); for (;;) { if ((__force unsigned int)filter < XA_MAX_MARKS)