linux-toradex.git/fs/compat.c, branch v2.6.16.50

skip data conversion in compat_sys_mount when data_page is NULL

2007-01-09T02:23:35+00:00

OpenVZ Linux kernel team has found a problem with mounting in compat mode.

Simple command "mount -t smbfs ..." on Fedora Core 5 distro in 32-bit mode
leads to oops:

Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP:
[] compat_sys_mount+0xd6/0x290
PGD 34d48067 PUD 34d03067 PMD 0
Oops: 0000 [1] SMP
CPU: 0
Modules linked in: iptable_nat simfs smbfs ip_nat ip_conntrack vzdquota
parport_pc lp parport 8021q bridge llc vznetdev vzmon nfs lockd sunrpc vzdev
iptable_filter af_packet xt_length ipt_ttl xt_tcpmss ipt_TCPMSS
iptable_mangle xt_limit ipt_tos ipt_REJECT ip_tables x_tables thermal
processor fan button battery asus_acpi ac uhci_hcd ehci_hcd usbcore i2c_i801
i2c_core e100 mii floppy ide_cd cdrom
Pid: 14656, comm: mount
RIP: 0060:[]  []
compat_sys_mount+0xd6/0x290
RSP: 0000:ffff810034d31f38  EFLAGS: 00010292
RAX: 000000000000002c RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff810034c86bc0 RSI: 0000000000000096 RDI: ffffffff8061fc90
RBP: ffff810034d31f78 R08: 0000000000000000 R09: 000000000000000d
R10: ffff810034d31e58 R11: 0000000000000001 R12: ffff810039dc3000
R13: 000000000805ea48 R14: 0000000000000000 R15: 00000000c0ed0000
FS:  0000000000000000(0000) GS:ffffffff80749000(0033) knlGS:00000000b7d556b0
CS:  0060 DS: 007b ES: 007b CR0: 000000008005003b
CR2: 0000000000000000 CR3: 0000000034d43000 CR4: 00000000000006e0
Process mount (pid: 14656, veid=300, threadinfo ffff810034d30000, task
ffff810034c86bc0)
Stack:  0000000000000000 ffff810034dd0000 ffff810034e4a000 000000000805ea48
 0000000000000000 0000000000000000 0000000000000000 0000000000000000
 000000000805ea48 ffffffff8021e64e 0000000000000000 0000000000000000
Call Trace:
 [] ia32_sysret+0x0/0xa

Code: 83 3b 06 0f 85 41 01 00 00 0f b7 43 0c 89 43 14 0f b7 43 0a
RIP  [] compat_sys_mount+0xd6/0x290
 RSP 
CR2: 0000000000000000

The problem is that data_page pointer can be NULL, so we should skip data
conversion in this case.

Signed-off-by: Andrey Mirkin 
Signed-off-by: Adrian Bunk

[PATCH] fs/compat.c: fix 'if (a |= b )' typo

2006-05-20T22:00:30+00:00

Mentioned by Mark Armbrust somewhere on Usenet.

Signed-off-by: Alexey Dobriyan 
Signed-off-by: David Woodhouse 
Cc: Ulrich Drepper 
Signed-off-by: Andrew Morton 
Signed-off-by: Chris Wright 
Signed-off-by: Greg Kroah-Hartman

[PATCH] LSM: add missing hook to do_compat_readv_writev()

2006-05-01T19:03:44+00:00

This patch addresses a flaw in LSM, where there is no mediation of readv()
and writev() in for 32-bit compatible apps using a 64-bit kernel.

This bug was discovered and fixed initially in the native readv/writev
code [1], but was not fixed in the compat code.  Thanks to Al for spotting
this one.

  [1] http://lwn.net/Articles/154282/

Signed-off-by: James Morris 
Signed-off-by: Al Viro 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Chris Wright

[PATCH] select: time comparison fixes

2006-02-17T21:59:28+00:00

I got all of these backwards.  We want to return

	min(input timeout, new timeout)

to userspace to prevent increasing the time-remaining value.

Thanks to Ernst Herzberg  for reporting and diagnosing.

Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] select: fix returned timeval

2006-02-12T05:41:11+00:00

With David Woodhouse 

select() presently has a habit of increasing the value of the user's
`timeout' argument on return.

We were writing back a timeout larger than the original.  We _deliberately_
round up, since we know we must wait at _least_ as long as the caller asks
us to.

The patch adds a couple of helper functions for magnitude comparison of
timespecs and of timevals, and uses them to prevent the various poll and
select functions from returning a timeout which is larger than the one which
was passed in.

The patch also fixes a bug in compat_sys_pselect7(): it was adding the new
timeout value to the old one and was returning that.  It should just return
the new timeout value.

(We have various handy timespec/timeval-to-from-nsec conversion functions in
time.h.  But this code open-codes it all).

Cc: "David S. Miller" 
Cc: Andi Kleen 
Cc: Ulrich Drepper 
Cc: Thomas Gleixner 
Cc: george anzinger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] compat: fix compat_sys_openat and friends

2006-02-02T06:04:33+00:00

Most of the 64 bit architectures will zero extend the first argument to
compat_sys_{openat,newfstatat,futimesat} which will fail if the 32 bit
syscall was passed AT_FDCWD (which is a small negative number).  Declare
the first argument to be an unsigned int which will force the correct
sign extension when the internal functions are called in each case.

Also, do some small white space cleanups in fs/compat.c.

Signed-off-by: Stephen Rothwell 
Acked-by: David S. Miller 
Signed-off-by: Linus Torvalds

[PATCH] compat_sys_pselect7() fix

2006-02-01T16:53:10+00:00

fs/compat.c: In function `compat_sys_pselect7':
fs/compat.c:1820: warning: passing arg 5 of `compat_core_sys_select' from incompatible pointer type

Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Fix regression added by ppoll/pselect code.

2006-01-20T06:11:31+00:00

The compat layer timeout handling changes in:

9f72949f679df06021c9e43886c9191494fdb007

are busted.  This is most easily seen with an X application
that uses sub-second select/poll timeout such as emacs.  You
hit a key and it takes a second or so before the app responds.

The two ROUND_UP() calls upon entry are using {tv,ts}_sec where it
should instead be using {tv_usec,ts_nsec}, which perfectly explains
the observed incorrect behavior.

Another bug shot down with git bisect.

Signed-off-by: David S. Miller 
Signed-off-by: Linus Torvalds

[PATCH] Add pselect/ppoll system call implementation

2006-01-19T03:20:30+00:00

The following implementation of ppoll() and pselect() system calls
depends on the architecture providing a TIF_RESTORE_SIGMASK flag in the
thread_info.

These system calls have to change the signal mask during their
operation, and signal handlers must be invoked using the new, temporary
signal mask. The old signal mask must be restored either upon successful
exit from the system call, or upon returning from the invoked signal
handler if the system call is interrupted. We can't simply restore the
original signal mask and return to userspace, since the restored signal
mask may actually block the signal which interrupted the system call.

The TIF_RESTORE_SIGMASK flag deals with this by causing the syscall exit
path to trap into do_signal() just as TIF_SIGPENDING does, and by
causing do_signal() to use the saved signal mask instead of the current
signal mask when setting up the stack frame for the signal handler -- or
by causing do_signal() to simply restore the saved signal mask in the
case where there is no handler to be invoked.

The first patch implements the sys_pselect() and sys_ppoll() system
calls, which are present only if TIF_RESTORE_SIGMASK is defined. That
#ifdef should go away in time when all architectures have implemented
it. The second patch implements TIF_RESTORE_SIGMASK for the PowerPC
kernel (in the -mm tree), and the third patch then removes the
arch-specific implementations of sys_rt_sigsuspend() and replaces them
with generic versions using the same trick.

The fourth and fifth patches, provided by David Howells, implement
TIF_RESTORE_SIGMASK for FR-V and i386 respectively, and the sixth patch
adds the syscalls to the i386 syscall table.

This patch:

Add the pselect() and ppoll() system calls, providing core routines usable by
the original select() and poll() system calls and also the new calls (with
their semantics w.r.t timeouts).

Signed-off-by: David Woodhouse 
Cc: Michael Kerrisk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] vfs: *at functions: core

2006-01-19T03:20:29+00:00

Here is a series of patches which introduce in total 13 new system calls
which take a file descriptor/filename pair instead of a single file
name.  These functions, openat etc, have been discussed on numerous
occasions.  They are needed to implement race-free filesystem traversal,
they are necessary to implement a virtual per-thread current working
directory (think multi-threaded backup software), etc.

We have in glibc today implementations of the interfaces which use the
/proc/self/fd magic.  But this code is rather expensive.  Here are some
results (similar to what Jim Meyering posted before).

The test creates a deep directory hierarchy on a tmpfs filesystem.  Then
rm -fr is used to remove all directories.  Without syscall support I get
this:

real    0m31.921s
user    0m0.688s
sys     0m31.234s

With syscall support the results are much better:

real    0m20.699s
user    0m0.536s
sys     0m20.149s

The interfaces are for obvious reasons currently not much used.  But they'll
be used.  coreutils (and Jeff's posixutils) are already using them.
Furthermore, code like ftw/fts in libc (maybe even glob) will also start using
them.  I expect a patch to make follow soon.  Every program which is walking
the filesystem tree will benefit.

Signed-off-by: Ulrich Drepper 
Signed-off-by: Alexey Dobriyan 
Cc: Christoph Hellwig 
Cc: Al Viro 
Acked-by: Ingo Molnar 
Cc: Michael Kerrisk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds