From: Paulo Alcantara pc@manguebit.com

mainline inclusion from mainline-v6.9-rc2 commit 24a9799aa8efecd0eb55a75e35f9d8e6400063aa category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QG1A CVE: CVE-2024-35870

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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The UAF bug is due to smb2_reconnect_server() accessing a session that is already being teared down by another thread that is executing __cifs_put_smb_ses(). This can happen when (a) the client has connection to the server but no session or (b) another thread ends up setting @ses->ses_status again to something different than SES_EXITING.

To fix this, we need to make sure to unconditionally set @ses->ses_status to SES_EXITING and prevent any other threads from setting a new status while we're still tearing it down.

The following can be reproduced by adding some delay to right after the ipc is freed in __cifs_put_smb_ses() - which will give smb2_reconnect_server() worker a chance to run and then accessing @ses->ipc:

kinit ... mount.cifs //srv/share /mnt/1 -o sec=krb5,nohandlecache,echo_interval=10 [disconnect srv] ls /mnt/1 &>/dev/null sleep 30 kdestroy [reconnect srv] sleep 10 umount /mnt/1 ... CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed CIFS: VFS: \srv Send error in SessSetup = -126 CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed CIFS: VFS: \srv Send error in SessSetup = -126 general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP NOPTI CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc2 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39 04/01/2014 Workqueue: cifsiod smb2_reconnect_server [cifs] RIP: 0010:__list_del_entry_valid_or_report+0x33/0xf0 Code: 4f 08 48 85 d2 74 42 48 85 c9 74 59 48 b8 00 01 00 00 00 00 ad de 48 39 c2 74 61 48 b8 22 01 00 00 00 00 74 69 <48> 8b 01 48 39 f8 75 7b 48 8b 72 08 48 39 c6 0f 85 88 00 00 00 b8 RSP: 0018:ffffc900001bfd70 EFLAGS: 00010a83 RAX: dead000000000122 RBX: ffff88810da53838 RCX: 6b6b6b6b6b6b6b6b RDX: 6b6b6b6b6b6b6b6b RSI: ffffffffc02f6878 RDI: ffff88810da53800 RBP: ffff88810da53800 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffff88810c064000 R13: 0000000000000001 R14: ffff88810c064000 R15: ffff8881039cc000 FS: 0000000000000000(0000) GS:ffff888157c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe3728b1000 CR3: 000000010caa4000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: <TASK> ? die_addr+0x36/0x90 ? exc_general_protection+0x1c1/0x3f0 ? asm_exc_general_protection+0x26/0x30 ? __list_del_entry_valid_or_report+0x33/0xf0 __cifs_put_smb_ses+0x1ae/0x500 [cifs] smb2_reconnect_server+0x4ed/0x710 [cifs] process_one_work+0x205/0x6b0 worker_thread+0x191/0x360 ? __pfx_worker_thread+0x10/0x10 kthread+0xe2/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK>

Cc: stable@vger.kernel.org Signed-off-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com Conflicts: fs/cifs/connect.c fs/smb/client/connect.c [Path is changed and related functions has been refactored for a long time] Signed-off-by: Long Li leo.lilong@huawei.com --- fs/cifs/connect.c | 48 ++++++++++++++++++----------------------------- 1 file changed, 18 insertions(+), 30 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 5cf5b58b9b66..0290c573db89 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -455,6 +455,8 @@ cifs_reconnect(struct TCP_Server_Info *server) spin_lock(&cifs_tcp_ses_lock); list_for_each(tmp, &server->smb_ses_list) { ses = list_entry(tmp, struct cifs_ses, smb_ses_list); + if (ses->status == CifsExiting) + continue; ses->need_reconnect = true; list_for_each(tmp2, &ses->tcon_list) { tcon = list_entry(tmp2, struct cifs_tcon, tcon_list); @@ -2814,34 +2816,6 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb_vol *volume_info) return rc; }

-/** - * cifs_free_ipc - helper to release the session IPC tcon - * - * Needs to be called everytime a session is destroyed - */ -static int -cifs_free_ipc(struct cifs_ses *ses) -{ - int rc = 0, xid; - struct cifs_tcon *tcon = ses->tcon_ipc; - - if (tcon == NULL) - return 0; - - if (ses->server->ops->tree_disconnect) { - xid = get_xid(); - rc = ses->server->ops->tree_disconnect(xid, tcon); - free_xid(xid); - } - - if (rc) - cifs_dbg(FYI, "failed to disconnect IPC tcon (rc=%d)\n", rc); - - tconInfoFree(tcon); - ses->tcon_ipc = NULL; - return rc; -} - static struct cifs_ses * cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb_vol *vol) { @@ -2863,8 +2837,9 @@ cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb_vol *vol)

void cifs_put_smb_ses(struct cifs_ses *ses) { - unsigned int rc, xid; + unsigned int rc = 0, xid; struct TCP_Server_Info *server = ses->server; + struct cifs_tcon *tcon = NULL;

cifs_dbg(FYI, "%s: ses_count=%d\n", __func__, ses->ses_count);

@@ -2881,10 +2856,23 @@ void cifs_put_smb_ses(struct cifs_ses *ses) spin_lock(&GlobalMid_Lock); if (ses->status == CifsGood) ses->status = CifsExiting; + tcon = ses->tcon_ipc; + ses->tcon_ipc = NULL; spin_unlock(&GlobalMid_Lock); spin_unlock(&cifs_tcp_ses_lock);

- cifs_free_ipc(ses); + if (tcon) { + if (ses->server->ops->tree_disconnect) { + xid = get_xid(); + rc = ses->server->ops->tree_disconnect(xid, tcon); + free_xid(xid); + } + + if (rc) + cifs_dbg(FYI, "failed to disconnect IPC tcon (rc=%d)\n", rc); + + tconInfoFree(tcon); + }

if (ses->status == CifsExiting && server->ops->logoff) { xid = get_xid();