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lib: stackinit: Adjust target string to 8 bytes for m68k

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For reasons I cannot understand, m68k moves the start of the stack frame
for consecutive calls to the same function if the function's test
variable is larger than 8 bytes. This was only happening for the char
array test (obviously), so adjust the length of the string for m68k
only. I want the array size to be longer than "unsigned long" for every
given architecture, so the other remain unchanged.

Additionally adjust the error message to be a bit more clear about
what's happened, and move the KUNIT check outside of the consecutive
calls to minimize what happens between them.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/lkml/a0d10d50-2720-4ecd-a2c6-c2c5e5aeee65@roeck-us.net/
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/r/CAMuHMdX_g1tbiUL9PUQdqaegrEzCNN3GtbSvSBFYAL4TzvstFg@mail.gmail.com
Closes: https://lore.kernel.org/r/CAMuHMdW6N40+0gGQ+LSrN64Mo4A0-ELAm0pR3gWQ0mNanyBuUQ@mail.gmail.com
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/all/a4bf4063-194f-4740-9c1d-88f9ab38b778@roeck-us.net
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2024-02-27 14:42:46 -08:00
parent d4be85d068
commit c2efa5387c
1 changed files with 16 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
lib/stackinit_kunit.c
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@ -63,7 +63,16 @@ static bool stackinit_range_contains(char *haystack_start, size_t haystack_size,
#define FETCH_ARG_STRING(var) var
#define FETCH_ARG_STRUCT(var) &var
/*
* On m68k, if the leaf function test variable is longer than 8 bytes,
* the start of the stack frame moves. 8 is sufficiently large to
* test m68k char arrays, but leave it at 16 for other architectures.
*/
#ifdef CONFIG_M68K
#define FILL_SIZE_STRING 8
#else
#define FILL_SIZE_STRING 16
#endif
#define INIT_CLONE_SCALAR /**/
#define INIT_CLONE_STRING [FILL_SIZE_STRING]
@ -165,19 +174,23 @@ static noinline void test_ ## name (struct kunit *test) \
/* Verify all bytes overwritten with 0xFF. */ \
for (sum = 0, i = 0; i < target_size; i++) \
sum += (check_buf[i] != 0xFF); \
KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
"leaf fill was not 0xFF!?\n"); \
/* Clear entire check buffer for later bit tests. */ \
memset(check_buf, 0x00, sizeof(check_buf)); \
/* Extract stack-defined variable contents. */ \
ignored = leaf_ ##name((unsigned long)&ignored, 0, \
FETCH_ARG_ ## which(zero)); \
/* \
* Delay the sum test to here to do as little as \
* possible between the two leaf function calls. \
*/ \
KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
"leaf fill was not 0xFF!?\n"); \
\
/* Validate that compiler lined up fill and target. */ \
KUNIT_ASSERT_TRUE_MSG(test, \
stackinit_range_contains(fill_start, fill_size, \
target_start, target_size), \
"stack fill missed target!? " \
"stackframe was not the same between calls!? " \
"(fill %zu wide, target offset by %d)\n", \
fill_size, \
(int)((ssize_t)(uintptr_t)fill_start - \