Commit 430f24f9 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

XArray: Fix infinite loop with entry at ULONG_MAX 



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: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: stable@vger.kernel.org
parent 82a95849

lib/test_xarray.c

+17 −0
Original line number Diff line number Diff line
@@ -1046,11 +1046,28 @@ static noinline void check_find_3(struct xarray *xa) 
	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);

}

lib/xarray.c

+3 −0
Original line number Diff line number Diff line
@@ -1849,6 +1849,9 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp, 
	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)

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