From: Konstantin Komarov almaz.alexandrovich@paragon-software.com
[ Upstream commit d57431c6f511bf020e474026d9f3123d7bfbea8c ]
In order not to call copy_to_user (from fiemap_fill_next_extent) we allocate memory in the kernel, fill it and copy it to user memory after up_read(run_lock).
Reported-by: syzbot+36bb70085ef6edc2ebb9@syzkaller.appspotmail.com Signed-off-by: Konstantin Komarov almaz.alexandrovich@paragon-software.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ntfs3/frecord.c | 75 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 72 insertions(+), 3 deletions(-)
diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c index 22fe7f58ad638..21f856e3fa77b 100644 --- a/fs/ntfs3/frecord.c +++ b/fs/ntfs3/frecord.c @@ -1896,6 +1896,47 @@ enum REPARSE_SIGN ni_parse_reparse(struct ntfs_inode *ni, struct ATTRIB *attr, return REPARSE_LINK; }
+/* + * fiemap_fill_next_extent_k - a copy of fiemap_fill_next_extent + * but it accepts kernel address for fi_extents_start + */ +static int fiemap_fill_next_extent_k(struct fiemap_extent_info *fieinfo, + u64 logical, u64 phys, u64 len, u32 flags) +{ + struct fiemap_extent extent; + struct fiemap_extent __user *dest = fieinfo->fi_extents_start; + + /* only count the extents */ + if (fieinfo->fi_extents_max == 0) { + fieinfo->fi_extents_mapped++; + return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0; + } + + if (fieinfo->fi_extents_mapped >= fieinfo->fi_extents_max) + return 1; + + if (flags & FIEMAP_EXTENT_DELALLOC) + flags |= FIEMAP_EXTENT_UNKNOWN; + if (flags & FIEMAP_EXTENT_DATA_ENCRYPTED) + flags |= FIEMAP_EXTENT_ENCODED; + if (flags & (FIEMAP_EXTENT_DATA_TAIL | FIEMAP_EXTENT_DATA_INLINE)) + flags |= FIEMAP_EXTENT_NOT_ALIGNED; + + memset(&extent, 0, sizeof(extent)); + extent.fe_logical = logical; + extent.fe_physical = phys; + extent.fe_length = len; + extent.fe_flags = flags; + + dest += fieinfo->fi_extents_mapped; + memcpy(dest, &extent, sizeof(extent)); + + fieinfo->fi_extents_mapped++; + if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max) + return 1; + return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0; +} + /* * ni_fiemap - Helper for file_fiemap(). * @@ -1906,6 +1947,8 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo, __u64 vbo, __u64 len) { int err = 0; + struct fiemap_extent __user *fe_u = fieinfo->fi_extents_start; + struct fiemap_extent *fe_k = NULL; struct ntfs_sb_info *sbi = ni->mi.sbi; u8 cluster_bits = sbi->cluster_bits; struct runs_tree *run; @@ -1953,6 +1996,18 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo, goto out; }
+ /* + * To avoid lock problems replace pointer to user memory by pointer to kernel memory. + */ + fe_k = kmalloc_array(fieinfo->fi_extents_max, + sizeof(struct fiemap_extent), + GFP_NOFS | __GFP_ZERO); + if (!fe_k) { + err = -ENOMEM; + goto out; + } + fieinfo->fi_extents_start = fe_k; + end = vbo + len; alloc_size = le64_to_cpu(attr->nres.alloc_size); if (end > alloc_size) @@ -2041,8 +2096,9 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo, if (vbo + dlen >= end) flags |= FIEMAP_EXTENT_LAST;
- err = fiemap_fill_next_extent(fieinfo, vbo, lbo, dlen, - flags); + err = fiemap_fill_next_extent_k(fieinfo, vbo, lbo, dlen, + flags); + if (err < 0) break; if (err == 1) { @@ -2062,7 +2118,8 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo, if (vbo + bytes >= end) flags |= FIEMAP_EXTENT_LAST;
- err = fiemap_fill_next_extent(fieinfo, vbo, lbo, bytes, flags); + err = fiemap_fill_next_extent_k(fieinfo, vbo, lbo, bytes, + flags); if (err < 0) break; if (err == 1) { @@ -2075,7 +2132,19 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
up_read(run_lock);
+ /* + * Copy to user memory out of lock + */ + if (copy_to_user(fe_u, fe_k, + fieinfo->fi_extents_max * + sizeof(struct fiemap_extent))) { + err = -EFAULT; + } + out: + /* Restore original pointer. */ + fieinfo->fi_extents_start = fe_u; + kfree(fe_k); return err; }