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sigreturn: fix use of user pointer in arch_extracontext_copy

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Matheus
2026-04-28 21:14:36 -03:00
parent 56bc12bdff
commit 37c3d7f98b
1 changed files with 15 additions and 7 deletions
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kernel-src/sys/syscalls/sigreturn.c
+15 -7
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@@ -11,12 +11,20 @@
__attribute__((noreturn)) void syscall_sigreturn(context_t *context) { __attribute__((noreturn)) void syscall_sigreturn(context_t *context) {
sigframe_t *sigframe = __builtin_alloca(ARCH_SIGFRAME_SIZE); sigframe_t *sigframe = __builtin_alloca(ARCH_SIGFRAME_SIZE);
int error = usercopy_fromuser(sigframe, (void *)CTX_SP(context), ARCH_SIGFRAME_SIZE); int error = usercopy_fromuser(sigframe, (void *)CTX_SP(context), ARCH_SIGFRAME_SIZE);
if (error || ARCH_CONTEXT_ISUSER(&sigframe->context) == false || !IS_USER_ADDRESS(CTX_IP(&sigframe->context))) { if (error)
printf("syscall_sigreturn: bad return stack or bad return information\n"); goto bad_return;
proc_terminate(SIGSEGV);
} // Rebase the embedded xsave pointer onto this in-kernel copy of the frame.
arch_sigframe_init(sigframe);
if (ARCH_CONTEXT_ISUSER(&sigframe->context) == false || !IS_USER_ADDRESS(CTX_IP(&sigframe->context)))
goto bad_return;
#ifdef __x86_64__ #ifdef __x86_64__
if (!IS_USER_ADDRESS((void *)sigframe->extracontext.gsbase) ||
!IS_USER_ADDRESS((void *)sigframe->extracontext.fsbase))
goto bad_return;
// CF PF AF ZF SF TF DF OF RF AC // CF PF AF ZF SF TF DF OF RF AC
sigframe->context.rflags &= 0x50DD5; sigframe->context.rflags &= 0x50DD5;
#endif #endif
@@ -29,15 +37,15 @@ __attribute__((noreturn)) void syscall_sigreturn(context_t *context) {
__assert(ARCH_CONTEXT_ISUSER(&sigframe->context)); __assert(ARCH_CONTEXT_ISUSER(&sigframe->context));
// XXX TODO FIXME there is a bug here that needs this temporarily.
arch_cpu_user_access_begin();
arch_extracontext_copy(&current_thread()->extracontext, &sigframe->extracontext); arch_extracontext_copy(&current_thread()->extracontext, &sigframe->extracontext);
arch_cpu_user_access_end();
ARCH_CONTEXT_THREADLOAD(current_thread(), context); ARCH_CONTEXT_THREADLOAD(current_thread(), context);
arch_context_switch(&sigframe->context); arch_context_switch(&sigframe->context);
// if we were to return normally, CTX_RET and CTX_ERRNO would be corrupted, // if we were to return normally, CTX_RET and CTX_ERRNO would be corrupted,
// so we will manually call arch_context_switch, which will jump to the right userland code // so we will manually call arch_context_switch, which will jump to the right userland code
// (and also check for pending signals again) // (and also check for pending signals again)
bad_return:
printf("syscall_sigreturn: bad return stack or bad return information\n");
proc_terminate(SIGSEGV);
__builtin_unreachable(); __builtin_unreachable();
} }