In 829c089f83, we disabled all
FORTIFY_SOURCE support when compiling under clang. At the time,
we didn't have proper test cases, and couldn't easily create targeted
clang tests.
This change re-enables FORTIFY_SOURCE support under clang for a
limited set of functions, where we have explicit unittests available.
The functions are:
* memcpy
* memmove
* strcpy
* strncpy
* strcat
* strncat
* memset
* strlen (with modifications)
* strchr (with modifications)
* strrchr (with modifications)
It may be possible, in the future, to enable other functions. However,
I need to write unittests first.
For strlen, strchr, and strrchr, clang unconditionally calls the
fortified version of the relevant function. If it doesn't know the
size of the buffer it's dealing with, it passes in ((size_t) -1),
which is the largest possible size_t.
I added two new clang specific unittest files, primarily copied
from fortify?_test.cpp.
I've also rebuild the entire system with these changes, and didn't
observe any obvious problems.
Change-Id: If12a15089bb0ffe93824b485290d05b14355fcaa
Define __errordecl and replace __attribute__((__error__("foo")))
with __errordecl. Make sure __errordecl is a no-op on clang, as it
generates a compile time warning.
Change-Id: Ifa1a2d3afd6881de9d479fc2adac6737871a2949
__strcat_chk and __strncat_chk are slightly inefficient,
because they end up traversing over the same memory region
two times.
This change optimizes __strcat_chk / __strncat_chk so they
only access the memory once. Although I haven't benchmarked these
changes, it should improve the performance of these functions.
__strlen_chk - expose this function, even if -D_FORTIFY_SOURCE
isn't defined. This is needed to compile libc itself without
-D_FORTIFY_SOURCE.
Change-Id: Id2c70dff55a276b47c59db27a03734d659f84b74
Add support for fortify source level 2 to strncpy.
This will enable detection of more areas where strncpy
is used inappropriately. For example, this would have detected
bug 8727221.
Move the fortify_source tests out of string_test.cpp, and
put it into fortify1_test.cpp.
Create a new fortify2_test.cpp file, which copies all
the tests in fortify1_test.cpp, and adds fortify_source level
2 specific tests.
Change-Id: Ica0fba531cc7d0609e4f23b8176739b13f7f7a83
Also add a more intention-revealing guard so we don't have loads of
places checking whether our inlining macro is defined.
Change-Id: I168860cedcfc798b07a5145bc48a125700265e47
Don't do the fortify_source checks if we can determine, at
compile time, that the provided operation is safe.
This avoids silliness like calling fortify source on things like:
size_t len = strlen("asdf");
printf("%d\n", len);
and allows the compiler to optimize this code to:
printf("%d\n", 4);
Defer to gcc's builtin functions instead of pointing our code
to the libc implementation.
Change-Id: I5e1dcb61946461c4afaaaa983e39f07c7a0df0ae
These checks haven't been as useful as I hoped, and it's
causing a false positive finding. Remove the overlap
compile time checks.
Change-Id: I5d45dde10ae4663d728230d41fa904adf20acaea
Clang and _FORTIFY_SOURCE are just plain incompatible with
each other. First of all, clang doesn't understand the
__attribute__((gnu_inline)) header. Second of all,
Clang doesn't have support for __builtin_va_arg_pack()
and __builtin_va_arg_pack_len() (see
http://clang.llvm.org/docs/UsersManual.html#c_unimpl_gcc)
Until we can resolve these issues, don't even try using
_FORTIFY_SOURCE under clang.
Change-Id: I81c2b8073bb3276fa9a4a6b93c427b641038356a
At this point, FORTIFY_SOURCE and clang are just plain incompatible.
Need to solve the underlying incompatibility first.
Change-Id: I3366477d19461e1ec93b1c30e0c7e8145b391b9b
This test is designed to detect code such as:
int main() {
char buf[10];
memcpy(buf, "1234567890", sizeof(buf));
size_t len = strlen(buf); // segfault here with _FORTIFY_SOURCE
printf("%d\n", len);
return 0;
}
or anytime strlen reads beyond an object boundary. This should
help address memory leakage vulnerabilities and make other
unrelated vulnerabilities harder to exploit.
Change-Id: I354b425be7bef4713c85f6bab0e9738445e00182
Two changes:
1) Detect memory read overruns.
For example:
int main() {
char buf[10];
memcpy(buf, "abcde", sizeof(buf));
sprintf("%s\n", buf);
}
because "abcde" is only 6 bytes, copying 10 bytes from it is a bug.
This particular bug will be detected at compile time. Other similar
bugs may be detected at runtime.
2) Detect overlapping buffers on memcpy()
It is a bug to call memcpy() on buffers which overlap. For
example, the following code is buggy:
char buf3[0x800];
char *first_half = &buf3[0x400];
char *second_half = &buf3[1];
memset(buf3, 0, sizeof(buf3));
memcpy(first_half, second_half, 0x400);
printf("1: %s\n", buf3);
We now detect this at compile and run time.
Change-Id: I092bd89f11f18e08e8a9dda0ca903aaea8e06d91
Prefix private functions with underscores, to prevent name
conflicts.
Use __error__ instead of error, since occasionally programs will
create their own "#define error ...".
Change-Id: I7bb171df58aec5627e61896032a140db547fd95d
Add strlcpy / strlcat support to FORTIFY_SOURCE. This allows
us to do consistency checks on to ensure we don't overflow buffers
when the compiler is able to tell us the size of the buffer we're
dealing with.
Unlike previous changes, this change DOES NOT use the compiler's
builtin support. Instead, we do everything the compiler would
normally do.
Change-Id: I47c099a911382452eafd711f8e9bfe7c2d0a0d22
Add _FORTIFY_SOURCE support for the following functions:
* memset
* bzero
Move the __BIONIC_FORTIFY_INLINE definition to cdefs.h so it
can be used from multiple header files.
Change-Id: Iead4d5e35de6ec97786d58ee12573f9b11135bb7
Add initial support for -D_FORTIFY_SOURCE to bionic for the
following functions:
* memcpy
* memmove
* strcpy
* strcat
* strncpy
* strncat
This change adds a new version of the above functions which passes
the size of the destination buffer to __builtin___*_chk.
If the compiler can determine, at compile time, that the destination
buffer is large enough, or the destination buffer can point to an object
of unknown size, then the check call is bypassed.
If the compiler can't make a compile time decision, then it calls
the __*_chk() function, which does a runtime buffer size check
These options are only enabled if the code is compiled with
-D_FORTIFY_SOURCE=1 or 2, and only when optimizations are enabled.
Please see
* http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
* http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
for additional details on FORTIFY_SOURCE.
Testing: Compiled the entire Android tree with -D_FORTIFY_SOURCE=1,
and verified that everything appears to be working properly.
Also created a test buffer overflow, and verified that it was
caught by this change.
Change-Id: I4fddb445bafe92b16845b22458d72e6dedd24fbc
cdefs.h: Introduce the __purefunc attribute, which allows us to mark
certain functions as being "pure".
http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
Many functions have no effects except the return value and their
return value depends only on the parameters and/or global variables.
Such a function can be subject to common subexpression elimination
and loop optimization just as an arithmetic operator would be.
string.h: Mark many commently used string functions as "pure", to
allow for additional compiler optimizations.
Change-Id: I42961f90f822b6dbcbc3fd72cdbe774a7adc8785
