Keith Owens <[email protected]> wrote:
>
> 2.6.13-rc4 + kdb, with lots of CONFIG_DEBUG options. There is an
> intermittent use after free in class_device_attr_show. Reboot with no
> changes and the problem does not always recur.
> ...
> ip is at class_device_attr_show+0x50/0xa0
> ...
>
> Call Trace:
> [<a000000100011f80>] show_stack+0x80/0xa0
> sp=e000003076ce79c0 bsp=e000003076ce10d8
> [<a0000001000127f0>] show_regs+0x850/0x880
> sp=e000003076ce7b90 bsp=e000003076ce1078
> [<a00000010003c000>] die+0x280/0x4a0
> sp=e000003076ce7ba0 bsp=e000003076ce1028
> [<a000000100060ad0>] ia64_do_page_fault+0x650/0xba0
> sp=e000003076ce7ba0 bsp=e000003076ce0fb8
> [<a00000010000b6c0>] ia64_leave_kernel+0x0/0x290
> sp=e000003076ce7c50 bsp=e000003076ce0fb8
> [<a0000001005807b0>] class_device_attr_show+0x50/0xa0
> sp=e000003076ce7e20 bsp=e000003076ce0f78
> [<a00000010025def0>] sysfs_read_file+0x2b0/0x360
> sp=e000003076ce7e20 bsp=e000003076ce0f08
> [<a000000100198a40>] vfs_read+0x1c0/0x360
> sp=e000003076ce7e20 bsp=e000003076ce0eb0
> [<a000000100198d80>] sys_read+0x80/0xe0
> sp=e000003076ce7e20 bsp=e000003076ce0e38
> [<a00000010000b520>] ia64_ret_from_syscall+0x0/0x20
> sp=e000003076ce7e30 bsp=e000003076ce0e38
It might help to know which file is being read from here.
The below patch will record the name of the most-recently-opened sysfs
file. You can print last_sysfs_file[] in the debugger or add the
appropriate printk to the ia64 code?
--- devel/fs/sysfs/file.c~sysfs-crash-debugging 2005-07-30 01:32:10.000000000 -0700
+++ devel-akpm/fs/sysfs/file.c 2005-07-30 02:09:01.000000000 -0700
@@ -6,6 +6,8 @@
#include <linux/fsnotify.h>
#include <linux/kobject.h>
#include <linux/namei.h>
+#include <linux/limits.h>
+
#include <asm/uaccess.h>
#include <asm/semaphore.h>
@@ -324,8 +326,14 @@ static int check_perm(struct inode * ino
return error;
}
+char last_sysfs_file[PATH_MAX];
+
static int sysfs_open_file(struct inode * inode, struct file * filp)
{
+ char *p = d_path(filp->f_dentry, sysfs_mount, last_sysfs_file,
+ sizeof(last_sysfs_file));
+ if (p)
+ memmove(last_sysfs_file, p, strlen(p));
return check_perm(inode,filp);
}
diff -puN arch/i386/kernel/traps.c~sysfs-crash-debugging arch/i386/kernel/traps.c
--- devel/arch/i386/kernel/traps.c~sysfs-crash-debugging 2005-07-30 01:32:10.000000000 -0700
+++ devel-akpm/arch/i386/kernel/traps.c 2005-07-30 01:32:10.000000000 -0700
@@ -96,6 +96,8 @@ static int kstack_depth_to_print = 24;
struct notifier_block *i386die_chain;
static DEFINE_SPINLOCK(die_notifier_lock);
+extern char last_sysfs_file[];
+
int register_die_notifier(struct notifier_block *nb)
{
int err = 0;
@@ -370,6 +372,7 @@ void die(const char * str, struct pt_reg
#endif
if (nl)
printk("\n");
+ printk(KERN_ALERT "last sysfs file: %s\n", last_sysfs_file);
#ifdef CONFIG_KGDB
/* This is about the only place we want to go to kgdb even if in
* user mode. But we must go in via a trap so within kgdb we will
_
-
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