diff options
author | Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> | 2006-11-25 20:09:39 +0100 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-11-25 22:28:34 +0100 |
commit | 5d48545e5e88ab7a27ba6a5cb1e8fff617754b61 (patch) | |
tree | 2da1a8d8e1ca4088cd91cc080f424b3e25e9423f /arch/um/os-Linux/helper.c | |
parent | [PATCH] usb: ati remote memleak fix (diff) | |
download | linux-5d48545e5e88ab7a27ba6a5cb1e8fff617754b61.tar.xz linux-5d48545e5e88ab7a27ba6a5cb1e8fff617754b61.zip |
[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>
Diffstat (limited to 'arch/um/os-Linux/helper.c')
-rw-r--r-- | arch/um/os-Linux/helper.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c index d13299cfa318..c7ad6306e22f 100644 --- a/arch/um/os-Linux/helper.c +++ b/arch/um/os-Linux/helper.c @@ -8,18 +8,21 @@ #include <unistd.h> #include <errno.h> #include <sched.h> +#include <limits.h> #include <sys/signal.h> #include <sys/wait.h> #include "user.h" #include "kern_util.h" #include "user_util.h" #include "os.h" +#include "um_malloc.h" struct helper_data { void (*pre_exec)(void*); void *pre_data; char **argv; int fd; + char *buf; }; /* Debugging aid, changed only from gdb */ @@ -41,9 +44,8 @@ static int helper_child(void *arg) } if (data->pre_exec != NULL) (*data->pre_exec)(data->pre_data); - execvp(argv[0], argv); - errval = -errno; - printk("helper_child - execve of '%s' failed - errno = %d\n", argv[0], errno); + errval = execvp_noalloc(data->buf, argv[0], argv); + printk("helper_child - execvp of '%s' failed - errno = %d\n", argv[0], -errval); os_write_file(data->fd, &errval, sizeof(errval)); kill(os_getpid(), SIGKILL); return 0; @@ -84,11 +86,13 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv, data.pre_data = pre_data; data.argv = argv; data.fd = fds[1]; + data.buf = __cant_sleep() ? um_kmalloc_atomic(PATH_MAX) : + um_kmalloc(PATH_MAX); pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data); if (pid < 0) { ret = -errno; printk("run_helper : clone failed, errno = %d\n", errno); - goto out_close; + goto out_free2; } close(fds[1]); @@ -109,6 +113,8 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv, CATCH_EINTR(waitpid(pid, NULL, 0)); } +out_free2: + kfree(data.buf); out_close: if (fds[1] != -1) close(fds[1]); |