From: Johannes Berg <johannes.berg@intel.com>
Date: Thu, 10 Oct 2024 14:14:12 +0000 (+0200)
Subject: um: restore process name
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=031acdcfb566ba18ffb57d51abf357a5e350424b;p=users%2Fjedix%2Flinux-maple.git

um: restore process name

After the execve() to disable ASLR, comm is now "exe",
which is a bit confusing. Use readlink() to get this
to the right name again.

Disable stack frame size warnings on main.o since it's
part of the initial userspace and can use larger stack.

Fixes: 68b9883cc16e ("um: Discover host_task_size from envp")
Link: https://patch.msgid.link/20241010161411.c576e2aeb3e5.I244d4f34b8a8555ee5bec0e1cf5027bce4cc491b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index 544e0b344c754..049dfa5bc9c69 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -12,6 +12,8 @@ obj-y = execvp.o file.o helper.o irq.o main.o mem.o process.o \
 
 CFLAGS_signal.o += -Wframe-larger-than=4096
 
+CFLAGS_main.o += -Wno-frame-larger-than
+
 obj-$(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA) += elf_aux.o
 
 USER_OBJS := $(user-objs-y) elf_aux.o execvp.o file.o helper.o irq.o \
diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index 8a52c49c53615..5e0cba5aee931 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -10,6 +10,7 @@
 #include <errno.h>
 #include <signal.h>
 #include <string.h>
+#include <limits.h>
 #include <sys/resource.h>
 #include <sys/personality.h>
 #include <as-layout.h>
@@ -112,8 +113,17 @@ int __init main(int argc, char **argv, char **envp)
 	/* Disable randomization and re-exec if it was changed successfully */
 	ret = personality(PER_LINUX | ADDR_NO_RANDOMIZE);
 	if (ret >= 0 && (ret & (PER_LINUX | ADDR_NO_RANDOMIZE)) !=
-			 (PER_LINUX | ADDR_NO_RANDOMIZE))
-		execve("/proc/self/exe", argv, envp);
+			 (PER_LINUX | ADDR_NO_RANDOMIZE)) {
+		char buf[PATH_MAX] = {};
+		ssize_t ret;
+
+		ret = readlink("/proc/self/exe", buf, sizeof(buf));
+		if (ret < 0 || ret >= sizeof(buf)) {
+			perror("readlink failure");
+			exit(1);
+		}
+		execve(buf, argv, envp);
+	}
 
 	set_stklim();