glibc/misc, branch master

Fix conditionals on mtrace-based tests (bug 31892)

2024-07-01T15:20:30Z

The conditionals for several mtrace-based tests in catgets, elf, libio, malloc, misc, nptl, posix, and stdio-common were incorrect leading to test failures when bootstrapping glibc without perl. The correct conditional for mtrace-based tests requires three checks: first checking for run-built-tests, then build-shared, and lastly that PERL is not equal to "no" (missing perl). Reviewed-by: Adhemerval Zanella

socket: Use may_alias on sockaddr structs (bug 19622)

2024-05-18T07:33:19Z

This supports common coding patterns. The GCC C front end before version 7 rejects the may_alias attribute on a struct definition if it was not present in a previous forward declaration, so this attribute can only be conditionally applied. This implements the spirit of the change in Austin Group issue 1641. Suggested-by: Marek Polacek Suggested-by: Jakub Jelinek Reviewed-by: Sam James Reviewed-by: Carlos O'Donell

misc: Add support for Linux uio.h RWF_NOAPPEND flag

2024-04-04T08:41:27Z

In Linux 6.9 a new flag is added to allow for Per-io operations to disable append mode even if a file was opened with the flag O_APPEND. This is done with the new RWF_NOAPPEND flag. This caused two test failures as these tests expected the flag 0x00000020 to be unused. Adding the flag definition now fixes these tests on Linux 6.9 (v6.9-rc1). FAIL: misc/tst-preadvwritev2 FAIL: misc/tst-preadvwritev64v2 This patch adds the flag, adjusts the test and adds details to documentation. Link: https://lore.kernel.org/all/20200831153207.GO3265@brightrain.aerifal.cx/ Reviewed-by: Adhemerval Zanella

Always define __USE_TIME_BITS64 when 64 bit time_t is used

2024-04-02T18:28:36Z

It was raised on libc-help [1] that some Linux kernel interfaces expect the libc to define __USE_TIME_BITS64 to indicate the time_t size for the kABI. Different than defined by the initial y2038 design document [2], the __USE_TIME_BITS64 is only defined for ABIs that support more than one time_t size (by defining the _TIME_BITS for each module). The 64 bit time_t redirects are now enabled using a different internal define (__USE_TIME64_REDIRECTS). There is no expected change in semantic or code generation. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, and arm-linux-gnueabi [1] https://sourceware.org/pipermail/libc-help/2024-January/006557.html [2] https://sourceware.org/glibc/wiki/Y2038ProofnessDesign Reviewed-by: DJ Delorie

cdefs: Drop access attribute for _FORTIFY_SOURCE=3 (BZ #31383)

2024-02-28T13:35:10Z

When passed a pointer to a zero-sized struct, the access attribute without the third argument misleads -Wstringop-overflow diagnostics to think that a function is writing 1 byte into the zero-sized structs. The attribute doesn't add that much value in this context, so drop it completely for _FORTIFY_SOURCE=3. Resolves: BZ #31383 Signed-off-by: Siddhesh Poyarekar Reviewed-by: Adhemerval Zanella

debug: Improve fcntl.h fortify warnings with clang

2024-02-27T13:52:59Z

It improves open, open64, openat, and openat64. The compile and runtime checks have similar coverage as with GCC. Checked on aarch64, armhf, x86_64, and i686. Reviewed-by: Carlos O'Donell Tested-by: Carlos O'Donell

syslog: Improve fortify with clang

2024-02-27T13:52:59Z

It improve fortify checks for syslog and vsyslog. The compile and runtime hecks have similar coverage as with GCC. The syslog fortify wrapper calls the va_arg version, since clang does not support __va_arg_pack. Checked on aarch64, armhf, x86_64, and i686. Reviewed-by: Carlos O'Donell Tested-by: Carlos O'Donell

cdefs.h: Add clang fortify directives

2024-02-27T13:52:57Z

For instance, the read wrapper is currently expanded as: extern __inline __attribute__((__always_inline__)) __attribute__((__artificial__)) __attribute__((__warn_unused_result__)) ssize_t read (int __fd, void *__buf, size_t __nbytes) { return __glibc_safe_or_unknown_len (__nbytes, sizeof (char), __glibc_objsize0 (__buf)) ? __read_alias (__fd, __buf, __nbytes) : __glibc_unsafe_len (__nbytes, sizeof (char), __glibc_objsize0 (__buf)) ? __read_chk_warn (__fd, __buf, __nbytes, __builtin_object_size (__buf, 0)) : __read_chk (__fd, __buf, __nbytes, __builtin_object_size (__buf, 0)); } The wrapper relies on __builtin_object_size call lowers to a constant at compile-time and many other operations in the wrapper depends on having a single, known value for parameters. Because this is impossible to have for function parameters, the wrapper depends heavily on inlining to work and While this is an entirely viable approach on GCC, it is not fully reliable on clang. This is because by the time llvm gets to inlining and optimizing, there is a minimal reliable source and type-level information available (more information on a more deep explanation on how to fortify wrapper works on clang [1]). To allow the wrapper to work reliably and with the same functionality as with GCC, clang requires a different approach: * __attribute__((diagnose_if(c, “str”, “warning”))) which is a function level attribute; if the compiler can determine that 'c' is true at compile-time, it will emit a warning with the text 'str1'. If it would be better to emit an error, the wrapper can use "error" instead of "warning". * __attribute__((overloadable)) which is also a function-level attribute; and it allows C++-style overloading to occur on C functions. * __attribute__((pass_object_size(n))) which is a parameter-level attribute; and it makes the compiler evaluate __builtin_object_size(param, n) at each call site of the function that has the parameter, and passes it in as a hidden parameter. This attribute has two side-effects that are key to how FORTIFY works: 1. It can overload solely on pass_object_size (e.g. there are two overloads of foo in void foo(char * __attribute__((pass_object_size(0))) c); void foo(char *); (The one with pass_object_size attribute has precende over the default one). 2. A function with at least one pass_object_size parameter can never have its address taken (and overload resolution respects this). Thus the read wrapper can be implemented as follows, without hindering any fortify coverage compile and runtime: extern __inline __attribute__((__always_inline__)) __attribute__((__artificial__)) __attribute__((__overloadable__)) __attribute__((__warn_unused_result__)) ssize_t read (int __fd, void *const __attribute__((pass_object_size (0))) __buf, size_t __nbytes) __attribute__((__diagnose_if__ ((((__builtin_object_size (__buf, 0)) != -1ULL && (__nbytes) > (__builtin_object_size (__buf, 0)) / (1))), "read called with bigger length than size of the destination buffer", "warning"))) { return (__builtin_object_size (__buf, 0) == (size_t) -1) ? __read_alias (__fd, __buf, __nbytes) : __read_chk (__fd, __buf, __nbytes, __builtin_object_size (__buf, 0)); } To avoid changing the current semantic for GCC, a set of macros is defined to enable the clang required attributes, along with some changes on internal macros to avoid the need to issue the symbol_chk symbols (which are done through the __diagnose_if__ attribute for clang). The read wrapper is simplified as: __fortify_function __attribute_overloadable__ __wur ssize_t read (int __fd, __fortify_clang_overload_arg0 (void *, ,__buf), size_t __nbytes) __fortify_clang_warning_only_if_bos0_lt (__nbytes, __buf, "read called with bigger length than " "size of the destination buffer") { return __glibc_fortify (read, __nbytes, sizeof (char), __glibc_objsize0 (__buf), __fd, __buf, __nbytes); } There is no expected semantic or code change when using GCC. Also, clang does not support __va_arg_pack, so variadic functions are expanded to call va_arg implementations. The error function must not have bodies (address takes are expanded to nonfortified calls), and with the __fortify_function compiler might still create a body with the C++ mangling name (due to the overload attribute). In this case, the function is defined with __fortify_function_error_function macro instead. [1] https://docs.google.com/document/d/1DFfZDICTbL7RqS74wJVIJ-YnjQOj1SaoqfhbgddFYSM/edit Checked on aarch64, armhf, x86_64, and i686. Reviewed-by: Carlos O'Donell Tested-by: Carlos O'Donell

syslog: Fix integer overflow in __vsyslog_internal (CVE-2023-6780)

2024-01-30T14:53:37Z

__vsyslog_internal calculated a buffer size by adding two integers, but did not first check if the addition would overflow. This commit fixes that. Reviewed-by: Carlos O'Donell Tested-by: Carlos O'Donell

syslog: Fix heap buffer overflow in __vsyslog_internal (CVE-2023-6779)

2024-01-30T14:53:37Z

__vsyslog_internal used the return value of snprintf/vsnprintf to calculate buffer sizes for memory allocation. If these functions (for any reason) failed and returned -1, the resulting buffer would be too small to hold output. This commit fixes that. All snprintf/vsnprintf calls are checked for negative return values and the function silently returns upon encountering them. Reviewed-by: Carlos O'Donell