Date: Sat, 25 Nov 2023 09:05:39 GMT From: Dimitry Andric <dim@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 1e4798e9677f - stable/14 - compiler-rt: avoid segfaults when re-exec'ing with ASLR Message-ID: <202311250905.3AP95dHE021434@gitrepo.freebsd.org>
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The branch stable/14 has been updated by dim: URL: https://cgit.FreeBSD.org/src/commit/?id=1e4798e9677f17a7cdc9a1873a0c6e008fc620d8 commit 1e4798e9677f17a7cdc9a1873a0c6e008fc620d8 Author: Dimitry Andric <dim@FreeBSD.org> AuthorDate: 2023-11-22 18:23:06 +0000 Commit: Dimitry Andric <dim@FreeBSD.org> CommitDate: 2023-11-25 09:05:09 +0000 compiler-rt: avoid segfaults when re-exec'ing with ASLR After 930a7c2ac67e ("compiler-rt: re-exec with ASLR disabled when necessary") and 96fe7c8ab0f6 ("compiler-rt: support ReExec() on FreeBSD"), binaries linked against the sanitizer libraries may segfault due to procctl(2) being intercepted. Instead, the non-intercepted internal_procctl() should be called. Similarly, the ReExec() function that re-executes the binary after turning off ASLR should not call elf_aux_info(3) and realpath(3), since these will also be intercepted. Instead, loop directly over the elf aux info vector to find the executable path, and avoid calling realpath(3) since it is actually unwanted for this use case. Fixes: 930a7c2ac67e, 96fe7c8ab0f6 MFC after: 3 days (cherry picked from commit 4c9a0adad18263ec8725d9bfc5f560c6ad1da8bd) --- .../compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp | 2 +- .../lib/sanitizer_common/sanitizer_linux_libcdep.cpp | 11 ++++++----- 2 files changed, 7 insertions(+), 6 deletions(-) diff --git a/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp index 3f544623c6fb..ebbd14eca72f 100644 --- a/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp +++ b/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp @@ -2323,7 +2323,7 @@ void CheckASLR() { "and binaries compiled with PIE\n" "ASLR will be disabled and the program re-executed.\n"); int aslr_ctl = PROC_ASLR_FORCE_DISABLE; - CHECK_NE(procctl(P_PID, 0, PROC_ASLR_CTL, &aslr_ctl), -1); + CHECK_NE(internal_procctl(P_PID, 0, PROC_ASLR_CTL, &aslr_ctl), -1); ReExec(); } # elif SANITIZER_PPC64V2 diff --git a/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp b/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp index ff62fc4af430..58310e05b359 100644 --- a/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp +++ b/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp @@ -56,6 +56,7 @@ // that, it was never implemented. So just define it to zero. #undef MAP_NORESERVE #define MAP_NORESERVE 0 +extern const Elf_Auxinfo *__elf_aux_vector; #endif #if SANITIZER_NETBSD @@ -947,11 +948,11 @@ void ReExec() { const char *pathname = "/proc/self/exe"; #if SANITIZER_FREEBSD - char exe_path[PATH_MAX]; - if (elf_aux_info(AT_EXECPATH, exe_path, sizeof(exe_path)) == 0) { - char link_path[PATH_MAX]; - if (realpath(exe_path, link_path)) - pathname = link_path; + for (const auto *aux = __elf_aux_vector; aux->a_type != AT_NULL; aux++) { + if (aux->a_type == AT_EXECPATH) { + pathname = static_cast<const char *>(aux->a_un.a_ptr); + break; + } } #elif SANITIZER_NETBSD static const int name[] = {
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