Messages in this thread | | | Subject | Re: [PATCH v4] f2fs: fix potential .flags overflow on 32bit architecture | From | Chao Yu <> | Date | Mon, 23 Mar 2020 11:22:01 +0800 |
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On 2020/3/23 10:57, Joe Perches wrote: > On Mon, 2020-03-23 at 10:41 +0800, Chao Yu wrote: >> 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. > [] >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > [] >> @@ -682,6 +682,47 @@ enum { > [] >> +/* used for f2fs_inode_info->flags */ >> +enum { > [] >> + FI_MAX, /* max flag, never be used */ >> +}; >> + >> +/* f2fs_inode_info.flags array size */ >> +#define FI_ARRAY_SIZE (BITS_TO_LONGS(FI_MAX)) > > Perhaps FI_ARRAY_SIZE isn't necessary. > >> + >> struct f2fs_inode_info { >> struct inode vfs_inode; /* serve a vfs inode */ >> unsigned long i_flags; /* keep an inode flags for ioctl */ >> @@ -694,7 +735,7 @@ struct f2fs_inode_info { >> umode_t i_acl_mode; /* keep file acl mode temporarily */ >> >> /* Use below internally in f2fs*/ >> - unsigned long flags; /* use to pass per-file flags */ >> + unsigned long flags[FI_ARRAY_SIZE]; /* use to pass per-file flags */ > > and BITS_TO_LONGS should be used here. > >> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c > [] >> @@ -362,7 +363,8 @@ static int do_read_inode(struct inode *inode) >> fi->i_flags = le32_to_cpu(ri->i_flags); >> if (S_ISREG(inode->i_mode)) >> fi->i_flags &= ~F2FS_PROJINHERIT_FL; >> - fi->flags = 0; >> + for (i = 0; i < FI_ARRAY_SIZE; i++) >> + fi->flags[i] = 0; > > And this could become > > bitmap_zero(fi->flags, BITS_TO_LONG(FI_MAX)); > > Is FI_ARRAY_SIZE used anywhere else?
Updated in v5, thanks.
Thanks,
> > . >
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