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Message-Id: <1497903987-21002-7-git-send-email-keescook@chromium.org>
Date: Mon, 19 Jun 2017 13:26:26 -0700
From: Kees Cook <keescook@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kees Cook <keescook@...omium.org>, Daniel Axtens <dja@...ens.net>,
Daniel Micay <danielmicay@...il.com>,
linux-kernel@...r.kernel.org,
Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [PATCH 6/7] powerpc: Make feature-fixup tests fortify-safe
From: Daniel Axtens <dja@...ens.net>
Testing the fortified string functions[1] would cause a kernel
panic on boot in test_feature_fixups() due to a buffer overflow
in memcmp.
This boils down to things like this:
extern unsigned int ftr_fixup_test1;
extern unsigned int ftr_fixup_test1_orig;
check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
We know that these are asm labels so it is safe to read up to
'size' bytes at those addresses.
However, because we have passed the address of a single unsigned
int to memcmp, the compiler believes the underlying object is in
fact a single unsigned int. So if size > sizeof(unsigned int),
there will be a panic at runtime.
We can fix this by changing the types: instead of calling the asm
labels unsigned ints, call them unsigned int[]s. Therefore the
size isn't incorrectly determined at compile time and we get a
regular unsafe memcmp and no panic.
[1] http://openwall.com/lists/kernel-hardening/2017/05/09/2
Suggested-by: Michael Ellerman <mpe@...erman.id.au>
Cc: Kees Cook <keescook@...omium.org>
Cc: Daniel Micay <danielmicay@...il.com>
Signed-off-by: Daniel Axtens <dja@...ens.net>
Tested-by: Andrew Donnellan <andrew.donnellan@....ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@....ibm.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
arch/powerpc/lib/feature-fixups.c | 180 +++++++++++++++++++-------------------
1 file changed, 90 insertions(+), 90 deletions(-)
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index f3917705c686..41cf5ae273cf 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -233,192 +233,192 @@ static long calc_offset(struct fixup_entry *entry, unsigned int *p)
static void test_basic_patching(void)
{
- extern unsigned int ftr_fixup_test1;
- extern unsigned int end_ftr_fixup_test1;
- extern unsigned int ftr_fixup_test1_orig;
- extern unsigned int ftr_fixup_test1_expected;
- int size = &end_ftr_fixup_test1 - &ftr_fixup_test1;
+ extern unsigned int ftr_fixup_test1[];
+ extern unsigned int end_ftr_fixup_test1[];
+ extern unsigned int ftr_fixup_test1_orig[];
+ extern unsigned int ftr_fixup_test1_expected[];
+ int size = end_ftr_fixup_test1 - ftr_fixup_test1;
fixup.value = fixup.mask = 8;
- fixup.start_off = calc_offset(&fixup, &ftr_fixup_test1 + 1);
- fixup.end_off = calc_offset(&fixup, &ftr_fixup_test1 + 2);
+ fixup.start_off = calc_offset(&fixup, ftr_fixup_test1 + 1);
+ fixup.end_off = calc_offset(&fixup, ftr_fixup_test1 + 2);
fixup.alt_start_off = fixup.alt_end_off = 0;
/* Sanity check */
- check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
+ check(memcmp(ftr_fixup_test1, ftr_fixup_test1_orig, size) == 0);
/* Check we don't patch if the value matches */
patch_feature_section(8, &fixup);
- check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
+ check(memcmp(ftr_fixup_test1, ftr_fixup_test1_orig, size) == 0);
/* Check we do patch if the value doesn't match */
patch_feature_section(0, &fixup);
- check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
+ check(memcmp(ftr_fixup_test1, ftr_fixup_test1_expected, size) == 0);
/* Check we do patch if the mask doesn't match */
- memcpy(&ftr_fixup_test1, &ftr_fixup_test1_orig, size);
- check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
+ memcpy(ftr_fixup_test1, ftr_fixup_test1_orig, size);
+ check(memcmp(ftr_fixup_test1, ftr_fixup_test1_orig, size) == 0);
patch_feature_section(~8, &fixup);
- check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
+ check(memcmp(ftr_fixup_test1, ftr_fixup_test1_expected, size) == 0);
}
static void test_alternative_patching(void)
{
- extern unsigned int ftr_fixup_test2;
- extern unsigned int end_ftr_fixup_test2;
- extern unsigned int ftr_fixup_test2_orig;
- extern unsigned int ftr_fixup_test2_alt;
- extern unsigned int ftr_fixup_test2_expected;
- int size = &end_ftr_fixup_test2 - &ftr_fixup_test2;
+ extern unsigned int ftr_fixup_test2[];
+ extern unsigned int end_ftr_fixup_test2[];
+ extern unsigned int ftr_fixup_test2_orig[];
+ extern unsigned int ftr_fixup_test2_alt[];
+ extern unsigned int ftr_fixup_test2_expected[];
+ int size = end_ftr_fixup_test2 - ftr_fixup_test2;
fixup.value = fixup.mask = 0xF;
- fixup.start_off = calc_offset(&fixup, &ftr_fixup_test2 + 1);
- fixup.end_off = calc_offset(&fixup, &ftr_fixup_test2 + 2);
- fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test2_alt);
- fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test2_alt + 1);
+ fixup.start_off = calc_offset(&fixup, ftr_fixup_test2 + 1);
+ fixup.end_off = calc_offset(&fixup, ftr_fixup_test2 + 2);
+ fixup.alt_start_off = calc_offset(&fixup, ftr_fixup_test2_alt);
+ fixup.alt_end_off = calc_offset(&fixup, ftr_fixup_test2_alt + 1);
/* Sanity check */
- check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
+ check(memcmp(ftr_fixup_test2, ftr_fixup_test2_orig, size) == 0);
/* Check we don't patch if the value matches */
patch_feature_section(0xF, &fixup);
- check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
+ check(memcmp(ftr_fixup_test2, ftr_fixup_test2_orig, size) == 0);
/* Check we do patch if the value doesn't match */
patch_feature_section(0, &fixup);
- check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
+ check(memcmp(ftr_fixup_test2, ftr_fixup_test2_expected, size) == 0);
/* Check we do patch if the mask doesn't match */
- memcpy(&ftr_fixup_test2, &ftr_fixup_test2_orig, size);
- check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
+ memcpy(ftr_fixup_test2, ftr_fixup_test2_orig, size);
+ check(memcmp(ftr_fixup_test2, ftr_fixup_test2_orig, size) == 0);
patch_feature_section(~0xF, &fixup);
- check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
+ check(memcmp(ftr_fixup_test2, ftr_fixup_test2_expected, size) == 0);
}
static void test_alternative_case_too_big(void)
{
- extern unsigned int ftr_fixup_test3;
- extern unsigned int end_ftr_fixup_test3;
- extern unsigned int ftr_fixup_test3_orig;
- extern unsigned int ftr_fixup_test3_alt;
- int size = &end_ftr_fixup_test3 - &ftr_fixup_test3;
+ extern unsigned int ftr_fixup_test3[];
+ extern unsigned int end_ftr_fixup_test3[];
+ extern unsigned int ftr_fixup_test3_orig[];
+ extern unsigned int ftr_fixup_test3_alt[];
+ int size = end_ftr_fixup_test3 - ftr_fixup_test3;
fixup.value = fixup.mask = 0xC;
- fixup.start_off = calc_offset(&fixup, &ftr_fixup_test3 + 1);
- fixup.end_off = calc_offset(&fixup, &ftr_fixup_test3 + 2);
- fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test3_alt);
- fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test3_alt + 2);
+ fixup.start_off = calc_offset(&fixup, ftr_fixup_test3 + 1);
+ fixup.end_off = calc_offset(&fixup, ftr_fixup_test3 + 2);
+ fixup.alt_start_off = calc_offset(&fixup, ftr_fixup_test3_alt);
+ fixup.alt_end_off = calc_offset(&fixup, ftr_fixup_test3_alt + 2);
/* Sanity check */
- check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
+ check(memcmp(ftr_fixup_test3, ftr_fixup_test3_orig, size) == 0);
/* Expect nothing to be patched, and the error returned to us */
check(patch_feature_section(0xF, &fixup) == 1);
- check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
+ check(memcmp(ftr_fixup_test3, ftr_fixup_test3_orig, size) == 0);
check(patch_feature_section(0, &fixup) == 1);
- check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
+ check(memcmp(ftr_fixup_test3, ftr_fixup_test3_orig, size) == 0);
check(patch_feature_section(~0xF, &fixup) == 1);
- check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
+ check(memcmp(ftr_fixup_test3, ftr_fixup_test3_orig, size) == 0);
}
static void test_alternative_case_too_small(void)
{
- extern unsigned int ftr_fixup_test4;
- extern unsigned int end_ftr_fixup_test4;
- extern unsigned int ftr_fixup_test4_orig;
- extern unsigned int ftr_fixup_test4_alt;
- extern unsigned int ftr_fixup_test4_expected;
- int size = &end_ftr_fixup_test4 - &ftr_fixup_test4;
+ extern unsigned int ftr_fixup_test4[];
+ extern unsigned int end_ftr_fixup_test4[];
+ extern unsigned int ftr_fixup_test4_orig[];
+ extern unsigned int ftr_fixup_test4_alt[];
+ extern unsigned int ftr_fixup_test4_expected[];
+ int size = end_ftr_fixup_test4 - ftr_fixup_test4;
unsigned long flag;
/* Check a high-bit flag */
flag = 1UL << ((sizeof(unsigned long) - 1) * 8);
fixup.value = fixup.mask = flag;
- fixup.start_off = calc_offset(&fixup, &ftr_fixup_test4 + 1);
- fixup.end_off = calc_offset(&fixup, &ftr_fixup_test4 + 5);
- fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test4_alt);
- fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test4_alt + 2);
+ fixup.start_off = calc_offset(&fixup, ftr_fixup_test4 + 1);
+ fixup.end_off = calc_offset(&fixup, ftr_fixup_test4 + 5);
+ fixup.alt_start_off = calc_offset(&fixup, ftr_fixup_test4_alt);
+ fixup.alt_end_off = calc_offset(&fixup, ftr_fixup_test4_alt + 2);
/* Sanity check */
- check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
+ check(memcmp(ftr_fixup_test4, ftr_fixup_test4_orig, size) == 0);
/* Check we don't patch if the value matches */
patch_feature_section(flag, &fixup);
- check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
+ check(memcmp(ftr_fixup_test4, ftr_fixup_test4_orig, size) == 0);
/* Check we do patch if the value doesn't match */
patch_feature_section(0, &fixup);
- check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
+ check(memcmp(ftr_fixup_test4, ftr_fixup_test4_expected, size) == 0);
/* Check we do patch if the mask doesn't match */
- memcpy(&ftr_fixup_test4, &ftr_fixup_test4_orig, size);
- check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
+ memcpy(ftr_fixup_test4, ftr_fixup_test4_orig, size);
+ check(memcmp(ftr_fixup_test4, ftr_fixup_test4_orig, size) == 0);
patch_feature_section(~flag, &fixup);
- check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
+ check(memcmp(ftr_fixup_test4, ftr_fixup_test4_expected, size) == 0);
}
static void test_alternative_case_with_branch(void)
{
- extern unsigned int ftr_fixup_test5;
- extern unsigned int end_ftr_fixup_test5;
- extern unsigned int ftr_fixup_test5_expected;
- int size = &end_ftr_fixup_test5 - &ftr_fixup_test5;
+ extern unsigned int ftr_fixup_test5[];
+ extern unsigned int end_ftr_fixup_test5[];
+ extern unsigned int ftr_fixup_test5_expected[];
+ int size = end_ftr_fixup_test5 - ftr_fixup_test5;
- check(memcmp(&ftr_fixup_test5, &ftr_fixup_test5_expected, size) == 0);
+ check(memcmp(ftr_fixup_test5, ftr_fixup_test5_expected, size) == 0);
}
static void test_alternative_case_with_external_branch(void)
{
- extern unsigned int ftr_fixup_test6;
- extern unsigned int end_ftr_fixup_test6;
- extern unsigned int ftr_fixup_test6_expected;
- int size = &end_ftr_fixup_test6 - &ftr_fixup_test6;
+ extern unsigned int ftr_fixup_test6[];
+ extern unsigned int end_ftr_fixup_test6[];
+ extern unsigned int ftr_fixup_test6_expected[];
+ int size = end_ftr_fixup_test6 - ftr_fixup_test6;
- check(memcmp(&ftr_fixup_test6, &ftr_fixup_test6_expected, size) == 0);
+ check(memcmp(ftr_fixup_test6, ftr_fixup_test6_expected, size) == 0);
}
static void test_cpu_macros(void)
{
- extern u8 ftr_fixup_test_FTR_macros;
- extern u8 ftr_fixup_test_FTR_macros_expected;
- unsigned long size = &ftr_fixup_test_FTR_macros_expected -
- &ftr_fixup_test_FTR_macros;
+ extern u8 ftr_fixup_test_FTR_macros[];
+ extern u8 ftr_fixup_test_FTR_macros_expected[];
+ unsigned long size = ftr_fixup_test_FTR_macros_expected -
+ ftr_fixup_test_FTR_macros;
/* The fixups have already been done for us during boot */
- check(memcmp(&ftr_fixup_test_FTR_macros,
- &ftr_fixup_test_FTR_macros_expected, size) == 0);
+ check(memcmp(ftr_fixup_test_FTR_macros,
+ ftr_fixup_test_FTR_macros_expected, size) == 0);
}
static void test_fw_macros(void)
{
#ifdef CONFIG_PPC64
- extern u8 ftr_fixup_test_FW_FTR_macros;
- extern u8 ftr_fixup_test_FW_FTR_macros_expected;
- unsigned long size = &ftr_fixup_test_FW_FTR_macros_expected -
- &ftr_fixup_test_FW_FTR_macros;
+ extern u8 ftr_fixup_test_FW_FTR_macros[];
+ extern u8 ftr_fixup_test_FW_FTR_macros_expected[];
+ unsigned long size = ftr_fixup_test_FW_FTR_macros_expected -
+ ftr_fixup_test_FW_FTR_macros;
/* The fixups have already been done for us during boot */
- check(memcmp(&ftr_fixup_test_FW_FTR_macros,
- &ftr_fixup_test_FW_FTR_macros_expected, size) == 0);
+ check(memcmp(ftr_fixup_test_FW_FTR_macros,
+ ftr_fixup_test_FW_FTR_macros_expected, size) == 0);
#endif
}
static void test_lwsync_macros(void)
{
- extern u8 lwsync_fixup_test;
- extern u8 end_lwsync_fixup_test;
- extern u8 lwsync_fixup_test_expected_LWSYNC;
- extern u8 lwsync_fixup_test_expected_SYNC;
- unsigned long size = &end_lwsync_fixup_test -
- &lwsync_fixup_test;
+ extern u8 lwsync_fixup_test[];
+ extern u8 end_lwsync_fixup_test[];
+ extern u8 lwsync_fixup_test_expected_LWSYNC[];
+ extern u8 lwsync_fixup_test_expected_SYNC[];
+ unsigned long size = end_lwsync_fixup_test -
+ lwsync_fixup_test;
/* The fixups have already been done for us during boot */
if (cur_cpu_spec->cpu_features & CPU_FTR_LWSYNC) {
- check(memcmp(&lwsync_fixup_test,
- &lwsync_fixup_test_expected_LWSYNC, size) == 0);
+ check(memcmp(lwsync_fixup_test,
+ lwsync_fixup_test_expected_LWSYNC, size) == 0);
} else {
- check(memcmp(&lwsync_fixup_test,
- &lwsync_fixup_test_expected_SYNC, size) == 0);
+ check(memcmp(lwsync_fixup_test,
+ lwsync_fixup_test_expected_SYNC, size) == 0);
}
}
--
2.7.4
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