3.16.61-rc1 review patch. If anyone has any objections, please let me know.
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From: Stefano Brivio sbrivio@redhat.com
commit 729c0c9dd55204f0c9a823ac8a7bfa83d36c7e78 upstream.
smb{2,3}_create_lease_buf() store a lease key in the lease context for later usage on a lease break.
In most paths, the key is currently sourced from data that happens to be on the stack near local variables for oplock in SMB2_open() callers, e.g. from open_shroot(), whereas smb2_open_file() properly allocates space on its stack for it.
The address of those local variables holding the oplock is then passed to create_lease_buf handlers via SMB2_open(), and 16 bytes near oplock are used. This causes a stack out-of-bounds access as reported by KASAN on SMB2.1 and SMB3 mounts (first out-of-bounds access is shown here):
[ 111.528823] BUG: KASAN: stack-out-of-bounds in smb3_create_lease_buf+0x399/0x3b0 [cifs] [ 111.530815] Read of size 8 at addr ffff88010829f249 by task mount.cifs/985 [ 111.532838] CPU: 3 PID: 985 Comm: mount.cifs Not tainted 4.18.0-rc3+ #91 [ 111.534656] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 111.536838] Call Trace: [ 111.537528] dump_stack+0xc2/0x16b [ 111.540890] print_address_description+0x6a/0x270 [ 111.542185] kasan_report+0x258/0x380 [ 111.544701] smb3_create_lease_buf+0x399/0x3b0 [cifs] [ 111.546134] SMB2_open+0x1ef8/0x4b70 [cifs] [ 111.575883] open_shroot+0x339/0x550 [cifs] [ 111.591969] smb3_qfs_tcon+0x32c/0x1e60 [cifs] [ 111.617405] cifs_mount+0x4f3/0x2fc0 [cifs] [ 111.674332] cifs_smb3_do_mount+0x263/0xf10 [cifs] [ 111.677915] mount_fs+0x55/0x2b0 [ 111.679504] vfs_kern_mount.part.22+0xaa/0x430 [ 111.684511] do_mount+0xc40/0x2660 [ 111.698301] ksys_mount+0x80/0xd0 [ 111.701541] do_syscall_64+0x14e/0x4b0 [ 111.711807] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 111.713665] RIP: 0033:0x7f372385b5fa [ 111.715311] Code: 48 8b 0d 99 78 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 66 78 2c 00 f7 d8 64 89 01 48 [ 111.720330] RSP: 002b:00007ffff27049d8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 [ 111.722601] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f372385b5fa [ 111.724842] RDX: 000055c2ecdc73b2 RSI: 000055c2ecdc73f9 RDI: 00007ffff270580f [ 111.727083] RBP: 00007ffff2705804 R08: 000055c2ee976060 R09: 0000000000001000 [ 111.729319] R10: 0000000000000000 R11: 0000000000000206 R12: 00007f3723f4d000 [ 111.731615] R13: 000055c2ee976060 R14: 00007f3723f4f90f R15: 0000000000000000
[ 111.735448] The buggy address belongs to the page: [ 111.737420] page:ffffea000420a7c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0 [ 111.739890] flags: 0x17ffffc0000000() [ 111.741750] raw: 0017ffffc0000000 0000000000000000 dead000000000200 0000000000000000 [ 111.744216] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 [ 111.746679] page dumped because: kasan: bad access detected
[ 111.750482] Memory state around the buggy address: [ 111.752562] ffff88010829f100: 00 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00 [ 111.754991] ffff88010829f180: 00 00 f2 f2 00 00 00 00 00 00 00 00 00 00 00 00 [ 111.757401] >ffff88010829f200: 00 00 00 00 00 f1 f1 f1 f1 01 f2 f2 f2 f2 f2 f2 [ 111.759801] ^ [ 111.762034] ffff88010829f280: f2 02 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 [ 111.764486] ffff88010829f300: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 111.766913] ==================================================================
Lease keys are however already generated and stored in fid data on open and create paths: pass them down to the lease context creation handlers and use them.
Suggested-by: Aurélien Aptel aaptel@suse.com Reviewed-by: Aurelien Aptel aaptel@suse.com Fixes: b8c32dbb0deb ("CIFS: Request SMB2.1 leases") Signed-off-by: Stefano Brivio sbrivio@redhat.com Signed-off-by: Steve French stfrench@microsoft.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/cifs/cifsglob.h | 2 +- fs/cifs/smb2file.c | 11 ++++------- fs/cifs/smb2ops.c | 9 +++------ fs/cifs/smb2pdu.c | 7 ++++--- fs/cifs/smb2pdu.h | 6 ++---- 5 files changed, 14 insertions(+), 21 deletions(-)
--- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -381,7 +381,7 @@ struct smb_version_operations { void (*set_oplock_level)(struct cifsInodeInfo *, __u32, unsigned int, bool *); /* create lease context buffer for CREATE request */ - char * (*create_lease_buf)(u8 *, u8); + char * (*create_lease_buf)(u8 *lease_key, u8 oplock); /* parse lease context buffer and return oplock/epoch info */ __u8 (*parse_lease_buf)(void *buf, unsigned int *epoch, char *lkey); int (*clone_range)(const unsigned int, struct cifsFileInfo *src_file, --- a/fs/cifs/smb2file.c +++ b/fs/cifs/smb2file.c @@ -41,7 +41,7 @@ smb2_open_file(const unsigned int xid, s int rc; __le16 *smb2_path; struct smb2_file_all_info *smb2_data = NULL; - __u8 smb2_oplock[17]; + __u8 smb2_oplock; struct cifs_fid *fid = oparms->fid;
smb2_path = cifs_convert_path_to_utf16(oparms->path, oparms->cifs_sb); @@ -58,12 +58,9 @@ smb2_open_file(const unsigned int xid, s }
oparms->desired_access |= FILE_READ_ATTRIBUTES; - *smb2_oplock = SMB2_OPLOCK_LEVEL_BATCH; + smb2_oplock = SMB2_OPLOCK_LEVEL_BATCH;
- if (oparms->tcon->ses->server->capabilities & SMB2_GLOBAL_CAP_LEASING) - memcpy(smb2_oplock + 1, fid->lease_key, SMB2_LEASE_KEY_SIZE); - - rc = SMB2_open(xid, oparms, smb2_path, smb2_oplock, smb2_data, NULL); + rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL); if (rc) goto out;
@@ -80,7 +77,7 @@ smb2_open_file(const unsigned int xid, s move_smb2_info_to_cifs(buf, smb2_data); }
- *oplock = *smb2_oplock; + *oplock = smb2_oplock; out: kfree(smb2_data); kfree(smb2_path); --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -1072,8 +1072,7 @@ smb2_create_lease_buf(u8 *lease_key, u8 if (!buf) return NULL;
- buf->lcontext.LeaseKeyLow = cpu_to_le64(*((u64 *)lease_key)); - buf->lcontext.LeaseKeyHigh = cpu_to_le64(*((u64 *)(lease_key + 8))); + memcpy(&buf->lcontext.LeaseKey, lease_key, SMB2_LEASE_KEY_SIZE); buf->lcontext.LeaseState = map_oplock_to_lease(oplock);
buf->ccontext.DataOffset = cpu_to_le16(offsetof @@ -1099,8 +1098,7 @@ smb3_create_lease_buf(u8 *lease_key, u8 if (!buf) return NULL;
- buf->lcontext.LeaseKeyLow = cpu_to_le64(*((u64 *)lease_key)); - buf->lcontext.LeaseKeyHigh = cpu_to_le64(*((u64 *)(lease_key + 8))); + memcpy(&buf->lcontext.LeaseKey, lease_key, SMB2_LEASE_KEY_SIZE); buf->lcontext.LeaseState = map_oplock_to_lease(oplock);
buf->ccontext.DataOffset = cpu_to_le16(offsetof @@ -1137,8 +1135,7 @@ smb3_parse_lease_buf(void *buf, unsigned if (lc->lcontext.LeaseFlags & SMB2_LEASE_FLAG_BREAK_IN_PROGRESS) return SMB2_OPLOCK_LEVEL_NOCHANGE; if (lease_key) - memcpy(lease_key, &lc->lcontext.LeaseKeyLow, - SMB2_LEASE_KEY_SIZE); + memcpy(lease_key, &lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE); return le32_to_cpu(lc->lcontext.LeaseState); }
--- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -1084,12 +1084,12 @@ parse_lease_state(struct TCP_Server_Info
static int add_lease_context(struct TCP_Server_Info *server, struct kvec *iov, - unsigned int *num_iovec, __u8 *oplock) + unsigned int *num_iovec, u8 *lease_key, __u8 *oplock) { struct smb2_create_req *req = iov[0].iov_base; unsigned int num = *num_iovec;
- iov[num].iov_base = server->ops->create_lease_buf(oplock+1, *oplock); + iov[num].iov_base = server->ops->create_lease_buf(lease_key, *oplock); if (iov[num].iov_base == NULL) return -ENOMEM; iov[num].iov_len = server->vals->create_lease_size; @@ -1212,7 +1212,8 @@ SMB2_open(const unsigned int xid, struct *oplock == SMB2_OPLOCK_LEVEL_NONE) req->RequestedOplockLevel = *oplock; else { - rc = add_lease_context(server, iov, &num_iovecs, oplock); + rc = add_lease_context(server, iov, &num_iovecs, + oparms->fid->lease_key, oplock); if (rc) { cifs_small_buf_release(req); kfree(copy_path); --- a/fs/cifs/smb2pdu.h +++ b/fs/cifs/smb2pdu.h @@ -510,16 +510,14 @@ struct create_context { #define SMB2_LEASE_KEY_SIZE 16
struct lease_context { - __le64 LeaseKeyLow; - __le64 LeaseKeyHigh; + u8 LeaseKey[SMB2_LEASE_KEY_SIZE]; __le32 LeaseState; __le32 LeaseFlags; __le64 LeaseDuration; } __packed;
struct lease_context_v2 { - __le64 LeaseKeyLow; - __le64 LeaseKeyHigh; + u8 LeaseKey[SMB2_LEASE_KEY_SIZE]; __le32 LeaseState; __le32 LeaseFlags; __le64 LeaseDuration;