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ftruncate: pass a signed offset

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commit 4b8e88e563b5f666446d002ad0dc1e6e8e7102b0 upstream.

The old ftruncate() syscall, using the 32-bit off_t misses a sign
extension when called in compat mode on 64-bit architectures.  As a
result, passing a negative length accidentally succeeds in truncating
to file size between 2GiB and 4GiB.

Changing the type of the compat syscall to the signed compat_off_t
changes the behavior so it instead returns -EINVAL.

The native entry point, the truncate() syscall and the corresponding
loff_t based variants are all correct already and do not suffer
from this mistake.

Fixes: 3f6d078d4acc ("fix compat truncate/ftruncate")
Reviewed-by: Christian Brauner <brauner@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit c329760749b5419769e57cb2be80955d2805f9c9)
[Vegard: fixed conflicts in context]
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
This commit is contained in:
Arnd Bergmann 2024-06-19 11:34:09 +02:00 committed by Vegard Nossum
parent e6522330b7
commit 5696aad6bf
3 changed files with 4 additions and 4 deletions
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4
fs/open.c
View File

@ -210,13 +210,13 @@ out:
return error;
}
SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
SYSCALL_DEFINE2(ftruncate, unsigned int, fd, off_t, length)
{
return do_sys_ftruncate(fd, length, 1);
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_off_t, length)
{
return do_sys_ftruncate(fd, length, 1);
}

2
include/linux/compat.h
View File

@ -563,7 +563,7 @@ asmlinkage long compat_sys_open_by_handle_at(int mountdirfd,
struct file_handle __user *handle,
int flags);
asmlinkage long compat_sys_truncate(const char __user *, compat_off_t);
asmlinkage long compat_sys_ftruncate(unsigned int, compat_ulong_t);
asmlinkage long compat_sys_ftruncate(unsigned int, compat_off_t);
asmlinkage long compat_sys_pselect6(int n, compat_ulong_t __user *inp,
compat_ulong_t __user *outp,
compat_ulong_t __user *exp,

2
include/linux/syscalls.h
View File

@ -426,7 +426,7 @@ asmlinkage long sys_mount(char __user *dev_name, char __user *dir_name,
asmlinkage long sys_umount(char __user *name, int flags);
asmlinkage long sys_oldumount(char __user *name);
asmlinkage long sys_truncate(const char __user *path, long length);
asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length);
asmlinkage long sys_ftruncate(unsigned int fd, off_t length);
asmlinkage long sys_stat(const char __user *filename,
struct __old_kernel_stat __user *statbuf);
asmlinkage long sys_statfs(const char __user * path,