From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
[ Upstream commit 6cd00a01f0c1ae6a852b09c59b8dd55cc6c35d1d ]
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.... 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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- fs/dcache.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/dcache.c b/fs/dcache.c index 807efaab838e..141651b0c766 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -278,7 +278,8 @@ 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; }