[PATCH] uml: make execvp safe for our usage
Reimplement execvp for our purposes - after we call fork() it is fundamentally
unsafe to use the kernel allocator - current is not valid there. So we simply
pass to our modified execvp() a preallocated buffer. This fixes a real bug
and works very well in testing (I've seen indirectly warning messages from the
forked thread - they went on the pipe connected to its stdout and where read
as a number by UML, when calling read_output(). I verified the obtained
number corresponded to "BUG:").
The added use of __cant_sleep() is not a new bug since __cant_sleep() is
already used in the same function - passing an atomicity parameter would be
better but it would require huge change, stating that this function must not
be called in atomic context and can sleep is a better idea (will make sure of
this gradually).
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index b418392..2f8c794 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -3,8 +3,8 @@
# Licensed under the GPL
#
-obj-y = aio.o elf_aux.o file.o helper.o irq.o main.o mem.o process.o sigio.o \
- signal.o start_up.o time.o trap.o tty.o uaccess.o umid.o tls.o \
+obj-y = aio.o elf_aux.o execvp.o file.o helper.o irq.o main.o mem.o process.o \
+ sigio.o signal.o start_up.o time.o trap.o tty.o uaccess.o umid.o tls.o \
user_syms.o util.o drivers/ sys-$(SUBARCH)/
obj-$(CONFIG_MODE_SKAS) += skas/
@@ -15,9 +15,9 @@
obj-$(CONFIG_TTY_LOG) += tty_log.o
user-objs-$(CONFIG_TTY_LOG) += tty_log.o
-USER_OBJS := $(user-objs-y) aio.o elf_aux.o file.o helper.o irq.o main.o mem.o \
- process.o sigio.o signal.o start_up.o time.o trap.o tty.o tls.o \
- uaccess.o umid.o util.o
+USER_OBJS := $(user-objs-y) aio.o elf_aux.o execvp.o file.o helper.o irq.o \
+ main.o mem.o process.o sigio.o signal.o start_up.o time.o trap.o tty.o \
+ tls.o uaccess.o umid.o util.o
CFLAGS_user_syms.o += -DSUBARCH_$(SUBARCH)