Messages in this thread | | | Subject | Re: [PATCH] f2fs: fix potential .flags overflow on 32bit architecture | From | Chao Yu <> | Date | Sun, 22 Mar 2020 21:18:56 +0800 |
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Hi,
On 2020-3-22 20:14, Ondřej Jirman wrote: > Hello, > > On Sun, Mar 22, 2020 at 06:13:27PM +0800, Chao Yu wrote: >> From: Chao Yu <yuchao0@huawei.com> >> >> f2fs_inode_info.flags is unsigned long variable, it has 32 bits >> in 32bit architecture, since we introduced FI_MMAP_FILE flag >> when we support data compression, we may access memory cross >> the border of .flags field, corrupting .i_sem field, result in >> below deadlock. >> >> To fix this issue, let's introduce .extra_flags to grab extra >> space to store those new flags. >> >> Call Trace: >> __schedule+0x8d0/0x13fc >> ? mark_held_locks+0xac/0x100 >> schedule+0xcc/0x260 >> rwsem_down_write_slowpath+0x3ab/0x65d >> down_write+0xc7/0xe0 >> f2fs_drop_nlink+0x3d/0x600 [f2fs] >> f2fs_delete_inline_entry+0x300/0x440 [f2fs] >> f2fs_delete_entry+0x3a1/0x7f0 [f2fs] >> f2fs_unlink+0x500/0x790 [f2fs] >> vfs_unlink+0x211/0x490 >> do_unlinkat+0x483/0x520 >> sys_unlink+0x4a/0x70 >> do_fast_syscall_32+0x12b/0x683 >> entry_SYSENTER_32+0xaa/0x102 >> >> Fixes: 4c8ff7095bef ("f2fs: support data compression") >> Signed-off-by: Chao Yu <yuchao0@huawei.com> >> --- >> fs/f2fs/f2fs.h | 26 ++++++++++++++++++++------ >> fs/f2fs/inode.c | 1 + >> 2 files changed, 21 insertions(+), 6 deletions(-) >> >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >> index fcafa68212eb..fcd22df2e9ca 100644 >> --- a/fs/f2fs/f2fs.h >> +++ b/fs/f2fs/f2fs.h >> @@ -695,6 +695,7 @@ struct f2fs_inode_info { >> >> /* Use below internally in f2fs*/ >> unsigned long flags; /* use to pass per-file flags */ >> + unsigned long extra_flags; /* extra flags */ >> struct rw_semaphore i_sem; /* protect fi info */ >> atomic_t dirty_pages; /* # of dirty pages */ >> f2fs_hash_t chash; /* hash value of given file name */ >> @@ -2569,7 +2570,7 @@ enum { >> }; >> >> static inline void __mark_inode_dirty_flag(struct inode *inode, >> - int flag, bool set) >> + unsigned long long flag, bool set) >> { >> switch (flag) { >> case FI_INLINE_XATTR: >> @@ -2588,20 +2589,33 @@ static inline void __mark_inode_dirty_flag(struct inode *inode, >> >> static inline void set_inode_flag(struct inode *inode, int flag) >> { >> - if (!test_bit(flag, &F2FS_I(inode)->flags)) >> - set_bit(flag, &F2FS_I(inode)->flags); >> + if ((1 << flag) <= sizeof(unsigned long)) { > > ^ this is wrong. Maybe you meant flag <= BITS_PER_LONG
Oh, my bad, I meant that, thanks for pointing out this. :)
> > And ditto for the same checks below. Maybe you can make flags an array of > BIT_WORD(max_flag_value) + 1 and skip the branches altogether?
That will be better, let me revise this patch.
Thanks,
> > thank you and regards, > o. > >> + if (!test_bit(flag, &F2FS_I(inode)->flags)) >> + set_bit(flag, &F2FS_I(inode)->flags); >> + } else { >> + if (!test_bit(flag - 32, &F2FS_I(inode)->extra_flags)) >> + set_bit(flag - 32, &F2FS_I(inode)->extra_flags); >> + } >> __mark_inode_dirty_flag(inode, flag, true); >> } >> >> static inline int is_inode_flag_set(struct inode *inode, int flag) >> { >> - return test_bit(flag, &F2FS_I(inode)->flags); >> + if ((1 << flag) <= sizeof(unsigned long)) >> + return test_bit(flag, &F2FS_I(inode)->flags); >> + else >> + return test_bit(flag - 32, &F2FS_I(inode)->extra_flags); >> } >> >> static inline void clear_inode_flag(struct inode *inode, int flag) >> { >> - if (test_bit(flag, &F2FS_I(inode)->flags)) >> - clear_bit(flag, &F2FS_I(inode)->flags); >> + if ((1 << flag) <= sizeof(unsigned long)) { >> + if (test_bit(flag, &F2FS_I(inode)->flags)) >> + clear_bit(flag, &F2FS_I(inode)->flags); >> + } else { >> + if (test_bit(flag - 32, &F2FS_I(inode)->extra_flags)) >> + clear_bit(flag - 32, &F2FS_I(inode)->extra_flags); >> + } >> __mark_inode_dirty_flag(inode, flag, false); >> } >> >> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c >> index 44e08bf2e2b4..ca924d7e0e30 100644 >> --- a/fs/f2fs/inode.c >> +++ b/fs/f2fs/inode.c >> @@ -363,6 +363,7 @@ static int do_read_inode(struct inode *inode) >> if (S_ISREG(inode->i_mode)) >> fi->i_flags &= ~F2FS_PROJINHERIT_FL; >> fi->flags = 0; >> + fi->extra_flags = 0; >> fi->i_advise = ri->i_advise; >> fi->i_pino = le32_to_cpu(ri->i_pino); >> fi->i_dir_level = ri->i_dir_level; >> -- >> 2.22.0 >>
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