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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-01-17 17:45:12 -0500
committerMatthew Wilcox (Oracle) <willy@infradead.org>2020-01-17 22:32:24 -0500
commit430f24f94c8a174d411a550d7b5529301922e67a (patch)
tree7a23f31ee6f3bca6a09e1ce0c23fa62d4e65c5e1 /lib
parent82a958497dc9120e0e8043da82273baedd255aaf (diff)
downloadlwn-430f24f94c8a174d411a550d7b5529301922e67a.tar.gz
lwn-430f24f94c8a174d411a550d7b5529301922e67a.zip
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: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: stable@vger.kernel.org
Diffstat (limited to 'lib')
-rw-r--r--lib/test_xarray.c17
-rw-r--r--lib/xarray.c3
2 files changed, 20 insertions, 0 deletions
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index c477f22a95cd..90584c63ca39 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -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);
}
diff --git a/lib/xarray.c b/lib/xarray.c
index bfaaa2c1f3fe..6ecf35c2e1da 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -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)