From: Luca Stefani <luca.stefani.ge1@xxxxxxxxx> Subject: ntfs: fix ntfs_test_inode and ntfs_init_locked_inode function type Clang's Control Flow Integrity (CFI) is a security mechanism that can help prevent JOP chains, deployed extensively in downstream kernels used in Android. Its deployment is hindered by mismatches in function signatures. For this case, we make callbacks match their intended function signature, and cast parameters within them rather than casting the callback when passed as a parameter. When running `mount -t ntfs ...` we observe the following trace: Call trace: __cfi_check_fail+0x1c/0x24 name_to_dev_t+0x0/0x404 iget5_locked+0x594/0x5e8 ntfs_fill_super+0xbfc/0x43ec mount_bdev+0x30c/0x3cc ntfs_mount+0x18/0x24 mount_fs+0x1b0/0x380 vfs_kern_mount+0x90/0x398 do_mount+0x5d8/0x1a10 SyS_mount+0x108/0x144 el0_svc_naked+0x34/0x38 Link: http://lkml.kernel.org/r/20200718112513.533800-1-luca.stefani.ge1@xxxxxxxxx Signed-off-by: Luca Stefani <luca.stefani.ge1@xxxxxxxxx> Tested-by: freak07 <michalechner92@xxxxxxxxxxxxxx> Acked-by: Anton Altaparmakov <anton@xxxxxxxxxx> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/ntfs/dir.c | 2 +- fs/ntfs/inode.c | 27 ++++++++++++++------------- fs/ntfs/inode.h | 4 +--- fs/ntfs/mft.c | 4 ++-- 4 files changed, 18 insertions(+), 19 deletions(-) --- a/fs/ntfs/dir.c~ntfs-fix-ntfs_test_inode-and-ntfs_init_locked_inode-function-type +++ a/fs/ntfs/dir.c @@ -1504,7 +1504,7 @@ static int ntfs_dir_fsync(struct file *f na.type = AT_BITMAP; na.name = I30; na.name_len = 4; - bmp_vi = ilookup5(vi->i_sb, vi->i_ino, (test_t)ntfs_test_inode, &na); + bmp_vi = ilookup5(vi->i_sb, vi->i_ino, ntfs_test_inode, &na); if (bmp_vi) { write_inode_now(bmp_vi, !datasync); iput(bmp_vi); --- a/fs/ntfs/inode.c~ntfs-fix-ntfs_test_inode-and-ntfs_init_locked_inode-function-type +++ a/fs/ntfs/inode.c @@ -30,10 +30,10 @@ /** * ntfs_test_inode - compare two (possibly fake) inodes for equality * @vi: vfs inode which to test - * @na: ntfs attribute which is being tested with + * @data: data which is being tested with * * Compare the ntfs attribute embedded in the ntfs specific part of the vfs - * inode @vi for equality with the ntfs attribute @na. + * inode @vi for equality with the ntfs attribute @data. * * If searching for the normal file/directory inode, set @na->type to AT_UNUSED. * @na->name and @na->name_len are then ignored. @@ -43,8 +43,9 @@ * NOTE: This function runs with the inode_hash_lock spin lock held so it is not * allowed to sleep. */ -int ntfs_test_inode(struct inode *vi, ntfs_attr *na) +int ntfs_test_inode(struct inode *vi, void *data) { + ntfs_attr *na = (ntfs_attr *)data; ntfs_inode *ni; if (vi->i_ino != na->mft_no) @@ -72,9 +73,9 @@ int ntfs_test_inode(struct inode *vi, nt /** * ntfs_init_locked_inode - initialize an inode * @vi: vfs inode to initialize - * @na: ntfs attribute which to initialize @vi to + * @data: data which to initialize @vi to * - * Initialize the vfs inode @vi with the values from the ntfs attribute @na in + * Initialize the vfs inode @vi with the values from the ntfs attribute @data in * order to enable ntfs_test_inode() to do its work. * * If initializing the normal file/directory inode, set @na->type to AT_UNUSED. @@ -87,8 +88,9 @@ int ntfs_test_inode(struct inode *vi, nt * NOTE: This function runs with the inode->i_lock spin lock held so it is not * allowed to sleep. (Hence the GFP_ATOMIC allocation.) */ -static int ntfs_init_locked_inode(struct inode *vi, ntfs_attr *na) +static int ntfs_init_locked_inode(struct inode *vi, void *data) { + ntfs_attr *na = (ntfs_attr *)data; ntfs_inode *ni = NTFS_I(vi); vi->i_ino = na->mft_no; @@ -131,7 +133,6 @@ static int ntfs_init_locked_inode(struct return 0; } -typedef int (*set_t)(struct inode *, void *); static int ntfs_read_locked_inode(struct inode *vi); static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi); static int ntfs_read_locked_index_inode(struct inode *base_vi, @@ -164,8 +165,8 @@ struct inode *ntfs_iget(struct super_blo na.name = NULL; na.name_len = 0; - vi = iget5_locked(sb, mft_no, (test_t)ntfs_test_inode, - (set_t)ntfs_init_locked_inode, &na); + vi = iget5_locked(sb, mft_no, ntfs_test_inode, + ntfs_init_locked_inode, &na); if (unlikely(!vi)) return ERR_PTR(-ENOMEM); @@ -225,8 +226,8 @@ struct inode *ntfs_attr_iget(struct inod na.name = name; na.name_len = name_len; - vi = iget5_locked(base_vi->i_sb, na.mft_no, (test_t)ntfs_test_inode, - (set_t)ntfs_init_locked_inode, &na); + vi = iget5_locked(base_vi->i_sb, na.mft_no, ntfs_test_inode, + ntfs_init_locked_inode, &na); if (unlikely(!vi)) return ERR_PTR(-ENOMEM); @@ -280,8 +281,8 @@ struct inode *ntfs_index_iget(struct ino na.name = name; na.name_len = name_len; - vi = iget5_locked(base_vi->i_sb, na.mft_no, (test_t)ntfs_test_inode, - (set_t)ntfs_init_locked_inode, &na); + vi = iget5_locked(base_vi->i_sb, na.mft_no, ntfs_test_inode, + ntfs_init_locked_inode, &na); if (unlikely(!vi)) return ERR_PTR(-ENOMEM); --- a/fs/ntfs/inode.h~ntfs-fix-ntfs_test_inode-and-ntfs_init_locked_inode-function-type +++ a/fs/ntfs/inode.h @@ -253,9 +253,7 @@ typedef struct { ATTR_TYPE type; } ntfs_attr; -typedef int (*test_t)(struct inode *, void *); - -extern int ntfs_test_inode(struct inode *vi, ntfs_attr *na); +extern int ntfs_test_inode(struct inode *vi, void *data); extern struct inode *ntfs_iget(struct super_block *sb, unsigned long mft_no); extern struct inode *ntfs_attr_iget(struct inode *base_vi, ATTR_TYPE type, --- a/fs/ntfs/mft.c~ntfs-fix-ntfs_test_inode-and-ntfs_init_locked_inode-function-type +++ a/fs/ntfs/mft.c @@ -958,7 +958,7 @@ bool ntfs_may_write_mft_record(ntfs_volu * dirty code path of the inode dirty code path when writing * $MFT occurs. */ - vi = ilookup5_nowait(sb, mft_no, (test_t)ntfs_test_inode, &na); + vi = ilookup5_nowait(sb, mft_no, ntfs_test_inode, &na); } if (vi) { ntfs_debug("Base inode 0x%lx is in icache.", mft_no); @@ -1019,7 +1019,7 @@ bool ntfs_may_write_mft_record(ntfs_volu vi = igrab(mft_vi); BUG_ON(vi != mft_vi); } else - vi = ilookup5_nowait(sb, na.mft_no, (test_t)ntfs_test_inode, + vi = ilookup5_nowait(sb, na.mft_no, ntfs_test_inode, &na); if (!vi) { /* _
