From: Matthew Wilcox (Oracle) willy@infradead.org
[ Upstream commit bd40b17ca49d7d110adf456e647701ce74de2241 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- lib/test_xarray.c | 18 ++++++++++++++++++ lib/xarray.c | 3 ++- 2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/lib/test_xarray.c b/lib/test_xarray.c index 55c14e8c88591..8c7d7a8468b88 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -12,6 +12,9 @@ static unsigned int tests_run; static unsigned int tests_passed;
+static const unsigned int order_limit = + IS_ENABLED(CONFIG_XARRAY_MULTI) ? BITS_PER_LONG : 1; + #ifndef XA_DEBUG # ifdef __KERNEL__ void xa_dump(const struct xarray *xa) { } @@ -959,6 +962,20 @@ static noinline void check_multi_find_2(struct xarray *xa) } }
+static noinline void check_multi_find_3(struct xarray *xa) +{ + unsigned int order; + + for (order = 5; order < order_limit; order++) { + unsigned long index = 1UL << (order - 5); + + XA_BUG_ON(xa, !xa_empty(xa)); + xa_store_order(xa, 0, order - 4, xa_mk_index(0), GFP_KERNEL); + XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT)); + xa_erase_index(xa, 0); + } +} + static noinline void check_find_1(struct xarray *xa) { unsigned long i, j, k; @@ -1081,6 +1098,7 @@ static noinline void check_find(struct xarray *xa) for (i = 2; i < 10; i++) check_multi_find_1(xa, i); check_multi_find_2(xa); + check_multi_find_3(xa); }
/* See find_swap_entry() in mm/shmem.c */ diff --git a/lib/xarray.c b/lib/xarray.c index 1d9fab7db8dad..acd1fad2e862a 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1839,7 +1839,8 @@ static bool xas_sibling(struct xa_state *xas) 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); }
/**