fs/dcache.c: fix kmemcheck splat at take_dentry_name_snapshot()
Since only dentry->d_name.len + 1 bytes out of DNAME_INLINE_LEN bytes
are initialized at __d_alloc(), we can't copy the whole size
unconditionally.
WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (ffff8fa27465ac50)
636f6e66696766732e746d70000000000010000000000000020000000188ffff
i i i i i i i i i i i i i u u u u u u u u u u i i i i i u u u u
^
RIP: 0010:take_dentry_name_snapshot+0x28/0x50
RSP: 0018:ffffa83000f5bdf8 EFLAGS: 00010246
RAX: 0000000000000020 RBX: ffff8fa274b20550 RCX: 0000000000000002
RDX: ffffa83000f5be40 RSI: ffff8fa27465ac50 RDI: ffffa83000f5be60
RBP: ffffa83000f5bdf8 R08: ffffa83000f5be48 R09: 0000000000000001
R10: ffff8fa27465ac00 R11: ffff8fa27465acc0 R12: ffff8fa27465ac00
R13: ffff8fa27465acc0 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f79737ac8c0(0000) GS:ffffffff8fc30000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8fa274c0b000 CR3: 0000000134aa7002 CR4: 00000000000606f0
take_dentry_name_snapshot+0x28/0x50
vfs_rename+0x128/0x870
SyS_rename+0x3b2/0x3d0
entry_SYSCALL_64_fastpath+0x1a/0xa4
0xffffffffffffffff
Link: http://lkml.kernel.org/r/201709131912.GBG39012.QMJLOVFSFFOOtH@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/dcache.c b/fs/dcache.c
index 8d2ec48..2e7e8d8 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -292,7 +292,8 @@ void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry
spin_unlock(&dentry->d_lock);
name->name = p->name;
} else {
- memcpy(name->inline_name, dentry->d_iname, DNAME_INLINE_LEN);
+ memcpy(name->inline_name, dentry->d_iname,
+ dentry->d_name.len + 1);
spin_unlock(&dentry->d_lock);
name->name = name->inline_name;
}
