[Sanitizers] Avoid overload ambiguity for interceptors #100986
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Since glibc 2.40 some functions like openat make use of overloads when built with `-D_FORTIFY_SOURCE=2`, see: https://github.com/bminor/glibc/blob/master/io/bits/fcntl2.h This means that doing something like `(uintptr_t) openat` or `(void *) openat` is now ambiguous, breaking the compiler-rt build on new glibc versions. Fix this by explicitly casting the symbol to the expected function type before casting it to an intptr. The expected type is obtained as `decltype(REAL(func))` so we don't have to repeat the signature from INTERCEPTOR in the INTERCEPT_FUNTION macro.
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@llvm/pr-subscribers-compiler-rt-sanitizer Author: Nikita Popov (nikic) ChangesSince glibc 2.40 some functions like openat make use of overloads when built with This means that doing something like Fix this by explicitly casting the symbol to the expected function type before casting it to an intptr. The expected type is obtained as Fixes #100754. Full diff: https://github.com/llvm/llvm-project/pull/100986.diff 1 Files Affected:
diff --git a/compiler-rt/lib/interception/interception_linux.h b/compiler-rt/lib/interception/interception_linux.h
index 433a3d9bd7fa7..2e01ff44578c3 100644
--- a/compiler-rt/lib/interception/interception_linux.h
+++ b/compiler-rt/lib/interception/interception_linux.h
@@ -28,12 +28,14 @@ bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
uptr func, uptr trampoline);
} // namespace __interception
-#define INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) \
- ::__interception::InterceptFunction( \
- #func, \
- (::__interception::uptr *)&REAL(func), \
- (::__interception::uptr)&(func), \
- (::__interception::uptr)&TRAMPOLINE(func))
+// Cast func to type of REAL(func) before casting to uptr in case it is an
+// overloaded function, which is the case for some glibc functions when
+// _FORTIFY_SOURCE is used. This disambiguates which overload to use.
+#define INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) \
+ ::__interception::InterceptFunction( \
+ #func, (::__interception::uptr *)&REAL(func), \
+ (::__interception::uptr)(decltype(REAL(func)))&(func), \
+ (::__interception::uptr) &TRAMPOLINE(func))
// dlvsym is a GNU extension supported by some other platforms.
#if SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
@@ -41,7 +43,7 @@ bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
::__interception::InterceptFunction( \
#func, symver, \
(::__interception::uptr *)&REAL(func), \
- (::__interception::uptr)&(func), \
+ (::__interception::uptr)(decltype(REAL(func)))&(func), \
(::__interception::uptr)&TRAMPOLINE(func))
#else
#define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
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You can test this locally with the following command:git-clang-format --diff 73c72f2c6505d5bc8b47bb0420f6cba5b24270fe 256149db05b803f22e7baadbccb8c0c097c7ee27 --extensions h -- compiler-rt/lib/interception/interception_linux.hView the diff from clang-format here.diff --git a/compiler-rt/lib/interception/interception_linux.h b/compiler-rt/lib/interception/interception_linux.h
index 2e01ff4457..0f0724419a 100644
--- a/compiler-rt/lib/interception/interception_linux.h
+++ b/compiler-rt/lib/interception/interception_linux.h
@@ -31,20 +31,19 @@ bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
// Cast func to type of REAL(func) before casting to uptr in case it is an
// overloaded function, which is the case for some glibc functions when
// _FORTIFY_SOURCE is used. This disambiguates which overload to use.
-#define INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) \
- ::__interception::InterceptFunction( \
- #func, (::__interception::uptr *)&REAL(func), \
- (::__interception::uptr)(decltype(REAL(func)))&(func), \
- (::__interception::uptr) &TRAMPOLINE(func))
+# define INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func) \
+ ::__interception::InterceptFunction( \
+ #func, (::__interception::uptr *)&REAL(func), \
+ (::__interception::uptr)(decltype(REAL(func)))&(func), \
+ (::__interception::uptr) & TRAMPOLINE(func))
// dlvsym is a GNU extension supported by some other platforms.
#if SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
-#define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
- ::__interception::InterceptFunction( \
- #func, symver, \
- (::__interception::uptr *)&REAL(func), \
- (::__interception::uptr)(decltype(REAL(func)))&(func), \
- (::__interception::uptr)&TRAMPOLINE(func))
+# define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
+ ::__interception::InterceptFunction( \
+ #func, symver, (::__interception::uptr *)&REAL(func), \
+ (::__interception::uptr)(decltype(REAL(func)))&(func), \
+ (::__interception::uptr) & TRAMPOLINE(func))
#else
#define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
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I can confirm that this fixes the build failure on Gentoo. |
vitalybuka
approved these changes
Jul 29, 2024
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Excellent. Thank you from the rtsan team @nikic! |
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/cherry-pick 155b7a1 |
llvmbot
pushed a commit
to llvmbot/llvm-project
that referenced
this pull request
Jul 30, 2024
Since glibc 2.40 some functions like openat make use of overloads when built with `-D_FORTIFY_SOURCE=2`, see: https://github.com/bminor/glibc/blob/master/io/bits/fcntl2.h This means that doing something like `(uintptr_t) openat` or `(void *) openat` is now ambiguous, breaking the compiler-rt build on new glibc versions. Fix this by explicitly casting the symbol to the expected function type before casting it to an intptr. The expected type is obtained as `decltype(REAL(func))` so we don't have to repeat the signature from INTERCEPTOR in the INTERCEPT_FUNTION macro. Fixes llvm#100754. (cherry picked from commit 155b7a1)
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/pull-request #101150 |
tru
pushed a commit
to llvmbot/llvm-project
that referenced
this pull request
Aug 1, 2024
Since glibc 2.40 some functions like openat make use of overloads when built with `-D_FORTIFY_SOURCE=2`, see: https://github.com/bminor/glibc/blob/master/io/bits/fcntl2.h This means that doing something like `(uintptr_t) openat` or `(void *) openat` is now ambiguous, breaking the compiler-rt build on new glibc versions. Fix this by explicitly casting the symbol to the expected function type before casting it to an intptr. The expected type is obtained as `decltype(REAL(func))` so we don't have to repeat the signature from INTERCEPTOR in the INTERCEPT_FUNTION macro. Fixes llvm#100754. (cherry picked from commit 155b7a1)
banach-space
pushed a commit
to banach-space/llvm-project
that referenced
this pull request
Aug 7, 2024
Since glibc 2.40 some functions like openat make use of overloads when built with `-D_FORTIFY_SOURCE=2`, see: https://github.com/bminor/glibc/blob/master/io/bits/fcntl2.h This means that doing something like `(uintptr_t) openat` or `(void *) openat` is now ambiguous, breaking the compiler-rt build on new glibc versions. Fix this by explicitly casting the symbol to the expected function type before casting it to an intptr. The expected type is obtained as `decltype(REAL(func))` so we don't have to repeat the signature from INTERCEPTOR in the INTERCEPT_FUNTION macro. Fixes llvm#100754.
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Since glibc 2.40 some functions like openat make use of overloads when built with
-D_FORTIFY_SOURCE=2, see:https://github.com/bminor/glibc/blob/master/io/bits/fcntl2.h
This means that doing something like
(uintptr_t) openator(void *) openatis now ambiguous, breaking the compiler-rt build on new glibc versions.Fix this by explicitly casting the symbol to the expected function type before casting it to an intptr. The expected type is obtained as
decltype(REAL(func))so we don't have to repeat the signature from INTERCEPTOR in the INTERCEPT_FUNTION macro.Fixes #100754.