XArray: Fix xa_find_next for large multi-index entries
Coverity pointed out that xas_sibling() was shifting xa_offset without
promoting it to an unsigned long first, so the shift could cause an
overflow and we'd get the wrong answer. The fix is obvious, and the
new test-case provokes UBSAN to report an error:
runtime error: shift exponent 60 is too large for 32-bit type 'int'
Fixes: 19c30f4dd092 ("XArray: Fix xa_find_after with multi-index entries")
Reported-by: Bjorn Helgaas <bhelgaas@google.com>
Reported-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: stable@vger.kernel.org
diff --git a/lib/xarray.c b/lib/xarray.c
index 1d9fab7..acd1fad 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1839,7 +1839,8 @@
if (!node)
return false;
mask = (XA_CHUNK_SIZE << node->shift) - 1;
- return (xas->xa_index & mask) > (xas->xa_offset << node->shift);
+ return (xas->xa_index & mask) >
+ ((unsigned long)xas->xa_offset << node->shift);
}
/**