Panic using rsync to msdosfs filesystem

[Kostik Belousov]

On Wed, Jul 02, 2008 at 03:23:33PM -0700, Doug Barton wrote:
> I have a western digital passport USB hard drive that I use for 
> backups. It's always worked fine in FreeBSD and Windows doing straight 
> copies. Today I tried to get fancy and use rsync and it blew up on me.
> 
> It is a large disk (160G) and I use the following options in fstab:
> /dev/da0s1  /mnt/wd  msdosfs  rw,noauto,-olarge,-m775  0  0
> 
> Using the following command line for rsync I get a panic as soon as I 
> hit return: rsync -vv --backup -u -rlt source/ destination/
> 
> I'm using -current as of r180191. Here is the stack trace:
> Unread portion of the kernel message buffer:
> panic: stack overflow detected; backtrace may be corrupted
> cpuid = 1
> Uptime: 1h52m1s
> Physical memory: 2029 MB
> Dumping 133 MB: 118 102 86 70 54 38 22 6
> 
> Reading symbols from /boot/modules/nvidia.ko...Reading symbols from 
> /boot/modules/nvidia.ko.symbols...done.
> done.
> Loaded symbols for /boot/modules/nvidia.ko
> Reading symbols from /boot/kernel/acpi.ko...Reading symbols from 
> /boot/kernel/acpi.ko.symbols...done.
> done.
> Loaded symbols for /boot/kernel/acpi.ko
> Reading symbols from /boot/kernel/if_bge.ko...Reading symbols from 
> /boot/kernel/if_bge.ko.symbols...done.
> done.
> Loaded symbols for /boot/kernel/if_bge.ko
> Reading symbols from /boot/kernel/linux.ko...Reading symbols from 
> /boot/kernel/linux.ko.symbols...done.
> done.
> Loaded symbols for /boot/kernel/linux.ko
> Reading symbols from /boot/kernel/msdosfs.ko...Reading symbols from 
> /boot/kernel/msdosfs.ko.symbols...done.
> done.
> Loaded symbols for /boot/kernel/msdosfs.ko
> #0  doadump () at pcpu.h:196
> 196		__asm __volatile("movl %%fs:0,%0" : "=r" (td));
> (kgdb) where
> #0  doadump () at pcpu.h:196
> #1  0xc057a9ce in boot (howto=260)
>     at /usr/local/src/sys/kern/kern_shutdown.c:418
> #2  0xc057ac93 in panic (fmt=Variable "fmt" is not available.
> ) at /usr/local/src/sys/kern/kern_shutdown.c:572
> #3  0xc059c5b2 in __stack_chk_fail ()
>     at /usr/local/src/sys/kern/stack_protector.c:17
> #4  0xc652384a in msdosfs_rename (ap=0xc644aca4)
>     at 
> /usr/local/src/sys/modules/msdosfs/../../fs/msdosfs/msdosfs_vnops.c:1286
> #5  0xc07b4df5 in VOP_RENAME_APV (vop=0xc6525cc0, a=0xe9e59c1c)
>     at vnode_if.c:1184
> #6  0xc0605619 in kern_renameat (td=0xc58f1d20, oldfd=-100,
>     old=0xbfbfc4a0 <Address 0xbfbfc4a0 out of bounds>, newfd=-100,
>     new=0xbfbfcca0 <Address 0xbfbfcca0 out of bounds>, 
> pathseg=UIO_USERSPACE)
>     at vnode_if.h:622
> #7  0xc06057a6 in kern_rename (td=0xc58f1d20,
>     from=0xbfbfc4a0 <Address 0xbfbfc4a0 out of bounds>,
>     to=0xbfbfcca0 <Address 0xbfbfcca0 out of bounds>, 
> pathseg=UIO_USERSPACE)
>     at /usr/local/src/sys/kern/vfs_syscalls.c:3526
> #8  0xc06057d9 in rename (td=0xc58f1d20, uap=0xe9e59cf8)
>     at /usr/local/src/sys/kern/vfs_syscalls.c:3503
> #9  0xc07a6283 in syscall (frame=0xe9e59d38)
>     at /usr/local/src/sys/i386/i386/trap.c:1081
> #10 0xc078bb80 in Xint0x80_syscall ()
>     at /usr/local/src/sys/i386/i386/exception.s:261
> #11 0x00000033 in ?? ()
> Previous frame inner to this frame (corrupt stack?)
> 
> 
> Let me know what I can do to help.

Looks like this is the first casuality of the -fstack-protector.
Try this:

diff --git a/sys/fs/msdosfs/msdosfs_vnops.c b/sys/fs/msdosfs/msdosfs_vnops.c
index 8a1484f..fe673e0 100644
--- a/sys/fs/msdosfs/msdosfs_vnops.c
+++ b/sys/fs/msdosfs/msdosfs_vnops.c
@@ -982,7 +982,7 @@ msdosfs_rename(ap)
 	struct componentname *tcnp = ap->a_tcnp;
 	struct componentname *fcnp = ap->a_fcnp;
 	struct denode *ip, *xp, *dp, *zp;
-	u_char toname[11], oldname[11];
+	u_char toname[12], oldname[11];
 	u_long from_diroffset, to_diroffset;
 	u_char to_count;
 	int doingdirectory = 0, newparent = 0;
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