Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH RFC] f2fs: fix compat F2FS_IOC_{MOVE, GARBAGE_COLLECT}_RANGE | From | Chao Yu <> | Date | Wed, 4 Nov 2020 10:52:13 +0800 |
| |
On 2020/11/4 10:29, Eric Biggers wrote: > On Wed, Nov 04, 2020 at 10:19:06AM +0800, Chao Yu wrote: >> Eric reported a ioctl bug in below link: >> >> https://lore.kernel.org/linux-f2fs-devel/20201103032234.GB2875@sol.localdomain/ >> >> That said, on some 32-bit architectures, u64 has only 32-bit alignment, >> notably i386 and x86_32, so that size of struct f2fs_gc_range compiled >> in x86_32 is 20 bytes, however the size in x86_64 is 24 bytes, binary >> compiled in x86_32 can not call F2FS_IOC_GARBAGE_COLLECT_RANGE successfully >> due to mismatched value of ioctl command in betweeen binary and f2fs >> module, similarly, F2FS_IOC_MOVE_RANGE will fail too. >> >> In this patch we introduce two ioctls for compatibility of above special >> 32-bit binary: >> - F2FS_IOC32_GARBAGE_COLLECT_RANGE >> - F2FS_IOC32_MOVE_RANGE >> >> Signed-off-by: Chao Yu <yuchao0@huawei.com> >> --- >> >> Jaegeuk, Eric, >> >> I have no 32-bit machine now, so I don't run any test on this patch, >> please take a look at this RFC patch first. > > You can test this by running a 32-bit binary on a machine with a 64-bit kernel. > E.g. on x86_64, compile a binary with 'gcc -m32'.
Ah, thanks for providing the option, I can try that.
> >> #ifdef CONFIG_COMPAT >> +static int f2fs_compat_ioc_gc_range(struct file *file, unsigned long arg) >> +{ >> + struct compat_f2fs_gc_range __user *urange; >> + struct f2fs_gc_range range; >> + int err; >> + >> + urange = compat_ptr(arg); >> + err = get_user(range.sync, &urange->sync); >> + err |= get_user(range.start, &urange->start); >> + err |= get_user(range.len, &urange->len); >> + if (err) >> + return -EFAULT; >> + if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(file))))) >> + return -EIO; >> + if (!f2fs_is_checkpoint_ready(F2FS_I_SB(file_inode(file)))) >> + return -ENOSPC; >> + return f2fs_ioc_gc_range(file, (unsigned long)&range); >> +} > > This won't work because f2fs_ioc_gc_range() expects a user pointer. You'll need > to make the native and compat versions do the copy from user separately, and > have them call a helper function that takes a pointer to the argument in kernel > memory.
Yes, I need to introduce function like __f2fs_ioc_gc_range() to accepted pointer parameter which points kernel memory.
Will do test and resend v2 soon.
Thanks,
> > - Eric > . >
| |