Commit b95ecee3 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Long Li
Browse files

ftruncate: pass a signed offset 

stable inclusion
from stable-v5.10.220
commit 84bf6b64a1a0dfc6de7e1b1c776d58d608e7865a
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGEOW
CVE: CVE-2024-42084

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=tags/v5.10.221&id=84bf6b64a1a0dfc6de7e1b1c776d58d608e7865a



--------------------------------

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: 3f6d078d ("fix compat truncate/ftruncate")
Reviewed-by: default avatarChristian Brauner <brauner@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarLong Li <leo.lilong@huawei.com>
parent 4ca5cfae

fs/open.c

+2 −2
Original line number Diff line number Diff line
@@ -200,13 +200,13 @@ long do_sys_ftruncate(unsigned int fd, loff_t length, int small) 
	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);

}

include/linux/compat.h

+1 −1
Original line number Diff line number Diff line
@@ -527,7 +527,7 @@ asmlinkage long compat_sys_fstatfs(unsigned int fd, 
asmlinkage long compat_sys_fstatfs64(unsigned int fd, compat_size_t sz,

				     struct compat_statfs64 __user *buf);

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);

/* No generic prototype for truncate64, ftruncate64, fallocate */

asmlinkage long compat_sys_openat(int dfd, const char __user *filename,

				  int flags, umode_t mode);

include/linux/syscalls.h

+1 −1
Original line number Diff line number Diff line
@@ -447,7 +447,7 @@ asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user *buf); 
asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz,

				struct statfs64 __user *buf);

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);

#if BITS_PER_LONG == 32

asmlinkage long sys_truncate64(const char __user *path, loff_t length);

asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length);