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authorKees Cook <keescook@chromium.org>2022-09-19 15:53:13 -0700
committerKees Cook <keescook@chromium.org>2023-01-05 12:08:29 -0800
commit439a1bcac648fe9b59210cde8991fb2acf37bdab (patch)
tree89f6e3cef476af5c3bb3e194b804e55217d29602 /drivers/misc
parentb2ba00c2a51793d916b662cb049b8f01c55d9e82 (diff)
fortify: Use __builtin_dynamic_object_size() when available
Since the commits starting with c37495d6254c ("slab: add __alloc_size attributes for better bounds checking"), the compilers have runtime allocation size hints available in some places. This was immediately available to CONFIG_UBSAN_BOUNDS, but CONFIG_FORTIFY_SOURCE needed updating to explicitly make use of the hints via the associated __builtin_dynamic_object_size() helper. Detect and use the builtin when it is available, increasing the accuracy of the mitigation. When runtime sizes are not available, __builtin_dynamic_object_size() falls back to __builtin_object_size(), leaving the existing bounds checking unchanged. Additionally update the VMALLOC_LINEAR_OVERFLOW LKDTM test to make the hint invisible, otherwise the architectural defense is not exercised (the buffer overflow is detected in the memset() rather than when it crosses the edge of the allocation). Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Tom Rix <trix@redhat.com> Cc: linux-hardening@vger.kernel.org Cc: llvm@lists.linux.dev Reviewed-by: Miguel Ojeda <ojeda@kernel.org> # include/linux/compiler_attributes.h Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/lkdtm/heap.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c
index 62516078a619..0ce4cbf6abda 100644
--- a/drivers/misc/lkdtm/heap.c
+++ b/drivers/misc/lkdtm/heap.c
@@ -31,6 +31,7 @@ static void lkdtm_VMALLOC_LINEAR_OVERFLOW(void)
char *one, *two;
one = vzalloc(PAGE_SIZE);
+ OPTIMIZER_HIDE_VAR(one);
two = vzalloc(PAGE_SIZE);
pr_info("Attempting vmalloc linear overflow ...\n");