From 61670b4d270c71219def1fbc9441debc2ac2e6e9 Mon Sep 17 00:00:00 2001 From: Lukas Straub Date: Fri, 26 Aug 2022 15:29:27 +0000 Subject: [PATCH 1/5] um: Cleanup syscall_handler_t cast in syscalls_32.h Like in f4f03f299a56ce4d73c5431e0327b3b6cb55ebb9 "um: Cleanup syscall_handler_t definition/cast, fix warning", remove the cast to to fix the compiler warning. Signed-off-by: Lukas Straub Acked-by: Randy Dunlap # build-tested Signed-off-by: Richard Weinberger --- arch/x86/um/shared/sysdep/syscalls_32.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/x86/um/shared/sysdep/syscalls_32.h b/arch/x86/um/shared/sysdep/syscalls_32.h index 68fd2cf526fd7e..f6e9f84397e792 100644 --- a/arch/x86/um/shared/sysdep/syscalls_32.h +++ b/arch/x86/um/shared/sysdep/syscalls_32.h @@ -6,10 +6,9 @@ #include #include -typedef long syscall_handler_t(struct pt_regs); +typedef long syscall_handler_t(struct syscall_args); extern syscall_handler_t *sys_call_table[]; #define EXECUTE_SYSCALL(syscall, regs) \ - ((long (*)(struct syscall_args)) \ - (*sys_call_table[syscall]))(SYSCALL_ARGS(®s->regs)) + ((*sys_call_table[syscall]))(SYSCALL_ARGS(®s->regs)) From d27fff3499671dc23a08efd01cdb8b3764a391c4 Mon Sep 17 00:00:00 2001 From: Lukas Straub Date: Fri, 26 Aug 2022 15:29:31 +0000 Subject: [PATCH 2/5] um: Cleanup compiler warning in arch/x86/um/tls_32.c arch.tls_array is statically allocated so checking for NULL doesn't make sense. This causes the compiler warning below. Remove the checks to silence these warnings. ../arch/x86/um/tls_32.c: In function 'get_free_idx': ../arch/x86/um/tls_32.c:68:13: warning: the comparison will always evaluate as 'true' for the address of 'tls_array' will never be NULL [-Waddress] 68 | if (!t->arch.tls_array) | ^ In file included from ../arch/x86/um/asm/processor.h:10, from ../include/linux/rcupdate.h:30, from ../include/linux/rculist.h:11, from ../include/linux/pid.h:5, from ../include/linux/sched.h:14, from ../arch/x86/um/tls_32.c:7: ../arch/x86/um/asm/processor_32.h:22:31: note: 'tls_array' declared here 22 | struct uml_tls_struct tls_array[GDT_ENTRY_TLS_ENTRIES]; | ^~~~~~~~~ ../arch/x86/um/tls_32.c: In function 'get_tls_entry': ../arch/x86/um/tls_32.c:243:13: warning: the comparison will always evaluate as 'true' for the address of 'tls_array' will never be NULL [-Waddress] 243 | if (!t->arch.tls_array) | ^ ../arch/x86/um/asm/processor_32.h:22:31: note: 'tls_array' declared here 22 | struct uml_tls_struct tls_array[GDT_ENTRY_TLS_ENTRIES]; | ^~~~~~~~~ Signed-off-by: Lukas Straub Acked-by: Randy Dunlap # build-tested Signed-off-by: Richard Weinberger --- arch/x86/um/tls_32.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/x86/um/tls_32.c b/arch/x86/um/tls_32.c index ac8eee093f9cd0..66162eafd8e8f8 100644 --- a/arch/x86/um/tls_32.c +++ b/arch/x86/um/tls_32.c @@ -65,9 +65,6 @@ static int get_free_idx(struct task_struct* task) struct thread_struct *t = &task->thread; int idx; - if (!t->arch.tls_array) - return GDT_ENTRY_TLS_MIN; - for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) if (!t->arch.tls_array[idx].present) return idx + GDT_ENTRY_TLS_MIN; @@ -240,9 +237,6 @@ static int get_tls_entry(struct task_struct *task, struct user_desc *info, { struct thread_struct *t = &task->thread; - if (!t->arch.tls_array) - goto clear; - if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) return -EINVAL; From 782b1f70f8a8b28571949d2ba43fe88b96d75ec3 Mon Sep 17 00:00:00 2001 From: Christian Lamparter Date: Sat, 6 Aug 2022 21:52:22 +0200 Subject: [PATCH 3/5] um: fix default console kernel parameter OpenWrt's UML with 5.15 was producing odd errors/warnings during preinit part of the early userspace portion: |[ 0.000000] Kernel command line: ubd0=root.img root=98:0 console=tty |[...] |[ 0.440000] random: jshn: uninitialized urandom read (4 bytes read) |[ 0.460000] random: jshn: uninitialized urandom read (4 bytes read) |/etc/preinit: line 47: can't create /dev/tty: No such device or address |/etc/preinit: line 48: can't create /dev/tty: No such device or address |/etc/preinit: line 58: can't open /dev/tty: No such device or address |[...] repeated many times That "/dev/tty" came from the command line (which is automatically added if no console= parameter was specified for the uml binary). The TLDP project tells the following about the /dev/tty: | /dev/tty stands for the controlling terminal (if any) for the current | process.[...] | /dev/tty is something like a link to the actually terminal device[..] The "(if any)" is important here, since it's possible for processes to not have a controlling terminal. I think this was a simple typo and the author wanted tty0 there. CC: Thomas Meyer Fixes: d7ffac33631b ("um: stdio_console: Make preferred console") Signed-off-by: Christian Lamparter Signed-off-by: Richard Weinberger --- arch/um/kernel/um_arch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index e0de60e503b983..d9e023c78f568f 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -33,7 +33,7 @@ #include "um_arch.h" #define DEFAULT_COMMAND_LINE_ROOT "root=98:0" -#define DEFAULT_COMMAND_LINE_CONSOLE "console=tty" +#define DEFAULT_COMMAND_LINE_CONSOLE "console=tty0" /* Changed in add_arg and setup_arch, which run before SMP is started */ static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 }; From 2975e4a282964dd14831e4612ac1b6b10745e5ba Mon Sep 17 00:00:00 2001 From: Vincent Whitchurch Date: Wed, 7 Sep 2022 12:05:33 +0200 Subject: [PATCH 4/5] um: Prevent KASAN splats in dump_stack() Use READ_ONCE_NOCHECK() when reading the stack to prevent KASAN splats when dump_stack() is used. Fixes: 5b301409e8bc5d7fad ("UML: add support for KASAN under x86_64") Signed-off-by: Vincent Whitchurch Reviewed-by: Dmitry Vyukov Signed-off-by: Richard Weinberger --- arch/um/kernel/sysrq.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c index 7452f70d50d069..746715379f12a8 100644 --- a/arch/um/kernel/sysrq.c +++ b/arch/um/kernel/sysrq.c @@ -48,7 +48,8 @@ void show_stack(struct task_struct *task, unsigned long *stack, break; if (i && ((i % STACKSLOTS_PER_LINE) == 0)) pr_cont("\n"); - pr_cont(" %08lx", *stack++); + pr_cont(" %08lx", READ_ONCE_NOCHECK(*stack)); + stack++; } printk("%sCall Trace:\n", loglvl); From bd71558d585ac61cfd799db7f25e78dca404dd7a Mon Sep 17 00:00:00 2001 From: David Gow Date: Wed, 21 Sep 2022 14:48:55 +0800 Subject: [PATCH 5/5] arch: um: Mark the stack non-executable to fix a binutils warning Since binutils 2.39, ld will print a warning if any stack section is executable, which is the default for stack sections on files without a .note.GNU-stack section. This was fixed for x86 in commit ffcf9c5700e4 ("x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments"), but remained broken for UML, resulting in several warnings: /usr/bin/ld: warning: arch/x86/um/vdso/vdso.o: missing .note.GNU-stack section implies executable stack /usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker /usr/bin/ld: warning: .tmp_vmlinux.kallsyms1 has a LOAD segment with RWX permissions /usr/bin/ld: warning: .tmp_vmlinux.kallsyms1.o: missing .note.GNU-stack section implies executable stack /usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker /usr/bin/ld: warning: .tmp_vmlinux.kallsyms2 has a LOAD segment with RWX permissions /usr/bin/ld: warning: .tmp_vmlinux.kallsyms2.o: missing .note.GNU-stack section implies executable stack /usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker /usr/bin/ld: warning: vmlinux has a LOAD segment with RWX permissions Link both the VDSO and vmlinux with -z noexecstack, fixing the warnings about .note.GNU-stack sections. In addition, pass --no-warn-rwx-segments to dodge the remaining warnings about LOAD segments with RWX permissions in the kallsyms objects. (Note that this flag is apparently not available on lld, so hide it behind a test for BFD, which is what the x86 patch does.) Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ffcf9c5700e49c0aee42dcba9a12ba21338e8136 Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107 Signed-off-by: David Gow Reviewed-by: Lukas Straub Tested-by: Lukas Straub Acked-by: Randy Dunlap # build-tested Signed-off-by: Richard Weinberger --- arch/um/Makefile | 8 ++++++++ arch/x86/um/vdso/Makefile | 2 +- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/um/Makefile b/arch/um/Makefile index f2fe63bfd819f5..f1d4d67157be0b 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -132,10 +132,18 @@ export LDS_ELF_FORMAT := $(ELF_FORMAT) # The wrappers will select whether using "malloc" or the kernel allocator. LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc +# Avoid binutils 2.39+ warnings by marking the stack non-executable and +# ignorning warnings for the kallsyms sections. +LDFLAGS_EXECSTACK = -z noexecstack +ifeq ($(CONFIG_LD_IS_BFD),y) +LDFLAGS_EXECSTACK += $(call ld-option,--no-warn-rwx-segments) +endif + LD_FLAGS_CMDLINE = $(foreach opt,$(KBUILD_LDFLAGS),-Wl,$(opt)) # Used by link-vmlinux.sh which has special support for um link export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE) +export LDFLAGS_vmlinux := $(LDFLAGS_EXECSTACK) # When cleaning we don't include .config, so we don't include # TT or skas makefiles and don't clean skas_ptregs.h. diff --git a/arch/x86/um/vdso/Makefile b/arch/x86/um/vdso/Makefile index 8c0396fd0e6f69..6fbe97c52c991e 100644 --- a/arch/x86/um/vdso/Makefile +++ b/arch/x86/um/vdso/Makefile @@ -65,7 +65,7 @@ quiet_cmd_vdso = VDSO $@ -Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \ sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@' -VDSO_LDFLAGS = -fPIC -shared -Wl,--hash-style=sysv +VDSO_LDFLAGS = -fPIC -shared -Wl,--hash-style=sysv -z noexecstack GCOV_PROFILE := n #