diff options
| author | Kees Cook <keescook@chromium.org> | 2021-08-18 20:48:55 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-08-18 23:28:51 +0300 |
| commit | e6d468d32cd084edd030a8bae76440b17b854b5c (patch) | |
| tree | e31a1277a3770907f2b290fea8713d3d31380b03 /drivers/misc/lkdtm | |
| parent | b8661450bc7f1f3dd746f8cac48534e0dfdc1cdf (diff) | |
| download | linux-e6d468d32cd084edd030a8bae76440b17b854b5c.tar.xz | |
lkdtm/heap: Avoid __alloc_size hint warning for VMALLOC_LINEAR_OVERFLOW
Once __alloc_size hints have been added, the compiler will (correctly!)
see this as an overflow. We are, however, trying to test for this
condition at run-time (not compile-time), so work around it with a
volatile int offset.
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210818174855.2307828-5-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc/lkdtm')
| -rw-r--r-- | drivers/misc/lkdtm/heap.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c index 3d9aae5821a0..8a92f5a800fa 100644 --- a/drivers/misc/lkdtm/heap.c +++ b/drivers/misc/lkdtm/heap.c @@ -13,6 +13,13 @@ static struct kmem_cache *a_cache; static struct kmem_cache *b_cache; /* + * Using volatile here means the compiler cannot ever make assumptions + * about this value. This means compile-time length checks involving + * this variable cannot be performed; only run-time checks. + */ +static volatile int __offset = 1; + +/* * If there aren't guard pages, it's likely that a consecutive allocation will * let us overflow into the second allocation without overwriting something real. */ @@ -24,7 +31,7 @@ void lkdtm_VMALLOC_LINEAR_OVERFLOW(void) two = vzalloc(PAGE_SIZE); pr_info("Attempting vmalloc linear overflow ...\n"); - memset(one, 0xAA, PAGE_SIZE + 1); + memset(one, 0xAA, PAGE_SIZE + __offset); vfree(two); vfree(one); |