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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2020-01-31 13:07:55 +0300 |
|---|---|---|
| committer | Matthew Wilcox (Oracle) <willy@infradead.org> | 2020-01-31 23:09:36 +0300 |
| commit | bd40b17ca49d7d110adf456e647701ce74de2241 (patch) | |
| tree | 5b08f821b4204ae3698a8763f63a8d66b73da381 | |
| parent | d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 (diff) | |
| download | linux-bd40b17ca49d7d110adf456e647701ce74de2241.tar.xz | |
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
| -rw-r--r-- | lib/test_xarray.c | 18 | ||||
| -rw-r--r-- | lib/xarray.c | 3 |
2 files changed, 20 insertions, 1 deletions
diff --git a/lib/test_xarray.c b/lib/test_xarray.c index 55c14e8c8859..8c7d7a8468b8 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 1d9fab7db8da..acd1fad2e862 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); } /** |