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kmod: make __request_module() killable (CVE-2012-4398) 

svn path=/dists/sid/linux/; revision=19592
This commit is contained in:
Ben Hutchings 2012-12-09 19:41:58 +00:00
parent 3ed90cbba3
commit 4e3a6433bd
7 changed files with 346 additions and 0 deletions
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1
debian/changelog vendored
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@ -95,6 +95,7 @@ linux (3.2.35-1) UNRELEASED; urgency=low
HP Folio 13-2000 (Closes: #692361)
* [x86] KVM: x86: invalid opcode oops on SET_SREGS with OSXSAVE bit set
(CVE-2012-4461)
* kmod: make __request_module() killable (CVE-2012-4398)
[ Ian Campbell ]
* [xen] add support for microcode updating. (Closes: #693053)

69
debian/patches/bugfix/all/kmod-introduce-call_modprobe-helper.patch vendored Normal file
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@ -0,0 +1,69 @@
From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 23 Mar 2012 15:02:49 -0700
Subject: [4/5] kmod: introduce call_modprobe() helper
commit 3e63a93b987685f02421e18b2aa452d20553a88b upstream.
No functional changes. Move the call_usermodehelper code from
__request_module() into the new simple helper, call_modprobe().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/kmod.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 685b246..56a29e8 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -60,6 +60,21 @@ static DECLARE_RWSEM(umhelper_sem);
*/
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
+static int call_modprobe(char *module_name, int wait)
+{
+ static char *envp[] = {
+ "HOME=/",
+ "TERM=linux",
+ "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
+ NULL
+ };
+
+ char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
+
+ return call_usermodehelper_fns(modprobe_path, argv, envp,
+ wait, NULL, NULL, NULL);
+}
+
/**
* __request_module - try to load a kernel module
* @wait: wait (or not) for the operation to complete
@@ -81,11 +96,6 @@ int __request_module(bool wait, const char *fmt, ...)
char module_name[MODULE_NAME_LEN];
unsigned int max_modprobes;
int ret;
- char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
- static char *envp[] = { "HOME=/",
- "TERM=linux",
- "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
- NULL };
static atomic_t kmod_concurrent = ATOMIC_INIT(0);
#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
static int kmod_loop_msg;
@@ -128,9 +138,7 @@ int __request_module(bool wait, const char *fmt, ...)
trace_module_request(module_name, wait, _RET_IP_);
- ret = call_usermodehelper_fns(modprobe_path, argv, envp,
- wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC,
- NULL, NULL, NULL);
+ ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
atomic_dec(&kmod_concurrent);
return ret;

78
debian/patches/bugfix/all/kmod-make-__request_module-killable.patch vendored Normal file
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@ -0,0 +1,78 @@
From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 23 Mar 2012 15:02:50 -0700
Subject: [5/5] kmod: make __request_module() killable
commit 1cc684ab75123efe7ff446eb821d44375ba8fa30 upstream.
As Tetsuo Handa pointed out, request_module() can stress the system
while the oom-killed caller sleeps in TASK_UNINTERRUPTIBLE.
The task T uses "almost all" memory, then it does something which
triggers request_module(). Say, it can simply call sys_socket(). This
in turn needs more memory and leads to OOM. oom-killer correctly
chooses T and kills it, but this can't help because it sleeps in
TASK_UNINTERRUPTIBLE and after that oom-killer becomes "disabled" by the
TIF_MEMDIE task T.
Make __request_module() killable. The only necessary change is that
call_modprobe() should kmalloc argv and module_name, they can't live in
the stack if we use UMH_KILLABLE. This memory is freed via
call_usermodehelper_freeinfo()->cleanup.
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/kmod.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 56a29e8..957a7aa 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -60,6 +60,12 @@ static DECLARE_RWSEM(umhelper_sem);
*/
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
+static void free_modprobe_argv(struct subprocess_info *info)
+{
+ kfree(info->argv[3]); /* check call_modprobe() */
+ kfree(info->argv);
+}
+
static int call_modprobe(char *module_name, int wait)
{
static char *envp[] = {
@@ -69,10 +75,26 @@ static int call_modprobe(char *module_name, int wait)
NULL
};
- char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
+ char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
+ if (!argv)
+ goto out;
+
+ module_name = kstrdup(module_name, GFP_KERNEL);
+ if (!module_name)
+ goto free_argv;
+
+ argv[0] = modprobe_path;
+ argv[1] = "-q";
+ argv[2] = "--";
+ argv[3] = module_name; /* check free_modprobe_argv() */
+ argv[4] = NULL;
return call_usermodehelper_fns(modprobe_path, argv, envp,
- wait, NULL, NULL, NULL);
+ wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL);
+free_argv:
+ kfree(argv);
+out:
+ return -ENOMEM;
}
/**

34
debian/patches/bugfix/all/usermodehelper-____call_usermodehelper-doesnt-need-do_exit.patch vendored Normal file
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@ -0,0 +1,34 @@
From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 23 Mar 2012 15:02:49 -0700
Subject: [3/5] usermodehelper: ____call_usermodehelper() doesn't need
do_exit()
commit 5b9bd473e3b8a8c6c4ae99be475e6e9b27568555 upstream.
Minor cleanup. ____call_usermodehelper() can simply return, no need to
call do_exit() explicitely.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/kmod.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 8341de9..685b246 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -188,7 +188,7 @@ static int ____call_usermodehelper(void *data)
/* Exec failed? */
fail:
sub_info->retval = retval;
- do_exit(0);
+ return 0;
}
void call_usermodehelper_freeinfo(struct subprocess_info *info)

105
debian/patches/bugfix/all/usermodehelper-implement-UMH_KILLABLE.patch vendored Normal file
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@ -0,0 +1,105 @@
From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 23 Mar 2012 15:02:47 -0700
Subject: [2/5] usermodehelper: implement UMH_KILLABLE
commit d0bd587a80960d7ba7e0c8396e154028c9045c54 upstream.
Implement UMH_KILLABLE, should be used along with UMH_WAIT_EXEC/PROC.
The caller must ensure that subprocess_info->path/etc can not go away
until call_usermodehelper_freeinfo().
call_usermodehelper_exec(UMH_KILLABLE) does
wait_for_completion_killable. If it fails, it uses
xchg(&sub_info->complete, NULL) to serialize with umh_complete() which
does the same xhcg() to access sub_info->complete.
If call_usermodehelper_exec wins, it can safely return. umh_complete()
should get NULL and call call_usermodehelper_freeinfo().
Otherwise we know that umh_complete() was already called, in this case
call_usermodehelper_exec() falls back to wait_for_completion() which
should succeed "very soon".
Note: UMH_NO_WAIT == -1 but it obviously should not be used with
UMH_KILLABLE. We delay the neccessary cleanup to simplify the back
porting.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/kmod.h | 2 ++
kernel/kmod.c | 27 +++++++++++++++++++++++++--
2 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 722f477..1b598585 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -54,6 +54,8 @@ enum umh_wait {
UMH_WAIT_PROC = 1, /* wait for the process to complete */
};
+#define UMH_KILLABLE 4 /* wait for EXEC/PROC killable */
+
struct subprocess_info {
struct work_struct work;
struct completion *complete;
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 8ea2594..f92f917 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -201,7 +201,15 @@ EXPORT_SYMBOL(call_usermodehelper_freeinfo);
static void umh_complete(struct subprocess_info *sub_info)
{
- complete(sub_info->complete);
+ struct completion *comp = xchg(&sub_info->complete, NULL);
+ /*
+ * See call_usermodehelper_exec(). If xchg() returns NULL
+ * we own sub_info, the UMH_KILLABLE caller has gone away.
+ */
+ if (comp)
+ complete(comp);
+ else
+ call_usermodehelper_freeinfo(sub_info);
}
/* Keventd can't block, but this (a child) can. */
@@ -252,6 +260,9 @@ static void __call_usermodehelper(struct work_struct *work)
enum umh_wait wait = sub_info->wait;
pid_t pid;
+ if (wait != UMH_NO_WAIT)
+ wait &= ~UMH_KILLABLE;
+
/* CLONE_VFORK: wait until the usermode helper has execve'd
* successfully We need the data structures to stay around
* until that is done. */
@@ -461,9 +472,21 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
queue_work(khelper_wq, &sub_info->work);
if (wait == UMH_NO_WAIT) /* task has freed sub_info */
goto unlock;
+
+ if (wait & UMH_KILLABLE) {
+ retval = wait_for_completion_killable(&done);
+ if (!retval)
+ goto wait_done;
+
+ /* umh_complete() will see NULL and free sub_info */
+ if (xchg(&sub_info->complete, NULL))
+ goto unlock;
+ /* fallthrough, umh_complete() was already called */
+ }
+
wait_for_completion(&done);
+wait_done:
retval = sub_info->retval;
-
out:
call_usermodehelper_freeinfo(sub_info);
unlock:

54
debian/patches/bugfix/all/usermodehelper-introduce-umh_complete.patch vendored Normal file
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@ -0,0 +1,54 @@
From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 23 Mar 2012 15:02:47 -0700
Subject: [1/5] usermodehelper: introduce umh_complete(sub_info)
commit b3449922502f5a161ee2b5022a33aec8472fbf18 upstream.
Preparation. Add the new trivial helper, umh_complete(). Currently it
simply does complete(sub_info->complete).
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/kmod.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/kmod.c b/kernel/kmod.c
index a0a8854..8ea2594 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -199,6 +199,11 @@ void call_usermodehelper_freeinfo(struct subprocess_info *info)
}
EXPORT_SYMBOL(call_usermodehelper_freeinfo);
+static void umh_complete(struct subprocess_info *sub_info)
+{
+ complete(sub_info->complete);
+}
+
/* Keventd can't block, but this (a child) can. */
static int wait_for_helper(void *data)
{
@@ -235,7 +240,7 @@ static int wait_for_helper(void *data)
sub_info->retval = ret;
}
- complete(sub_info->complete);
+ umh_complete(sub_info);
return 0;
}
@@ -269,7 +274,7 @@ static void __call_usermodehelper(struct work_struct *work)
case UMH_WAIT_EXEC:
if (pid < 0)
sub_info->retval = pid;
- complete(sub_info->complete);
+ umh_complete(sub_info);
}
}

5
debian/patches/series vendored
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@ -423,3 +423,8 @@ bugfix/all/firmware-remove-redundant-log-messages-from-drivers.patch
bugfix/x86/ACPI-video-ignore-BIOS-initial-backlight-value-for-H.patch
bugfix/x86/KVM-x86-invalid-opcode-oops-on-SET_SREGS-with-OSXSAV.patch
bugfix/all/usermodehelper-introduce-umh_complete.patch
bugfix/all/usermodehelper-implement-UMH_KILLABLE.patch
bugfix/all/usermodehelper-____call_usermodehelper-doesnt-need-do_exit.patch
bugfix/all/kmod-introduce-call_modprobe-helper.patch
bugfix/all/kmod-make-__request_module-killable.patch