From: Namjae Jeon Date: Sat, 24 Jan 2026 01:55:46 +0000 (+0900) Subject: ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=010eb01ce23b34b50531448b0da391c7f05a72af;p=thirdparty%2Flinux.git ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths The problem occurs when a signed request fails smb2 signature verification check. In __process_request(), if check_sign_req() returns an error, set_smb2_rsp_status(work, STATUS_ACCESS_DENIED) is called. set_smb2_rsp_status() set work->next_smb2_rcv_hdr_off as zero. By resetting next_smb2_rcv_hdr_off to zero, the pointer to the next command in the chain is lost. Consequently, is_chained_smb2_message() continues to point to the same request header instead of advancing. If the header's NextCommand field is non-zero, the function returns true, causing __handle_ksmbd_work() to repeatedly process the same failed request in an infinite loop. This results in the kernel log being flooded with "bad smb2 signature" messages and high CPU usage. This patch fixes the issue by changing the return value from SERVER_HANDLER_CONTINUE to SERVER_HANDLER_ABORT. This ensures that the processing loop terminates immediately rather than attempting to continue from an invalidated offset. Reported-by: tianshuo han Cc: stable@vger.kernel.org Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c index 554ae90df906d..d2410a3f163ae 100644 --- a/fs/smb/server/server.c +++ b/fs/smb/server/server.c @@ -126,21 +126,21 @@ static int __process_request(struct ksmbd_work *work, struct ksmbd_conn *conn, andx_again: if (command >= conn->max_cmds) { conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER); - return SERVER_HANDLER_CONTINUE; + return SERVER_HANDLER_ABORT; } cmds = &conn->cmds[command]; if (!cmds->proc) { ksmbd_debug(SMB, "*** not implemented yet cmd = %x\n", command); conn->ops->set_rsp_status(work, STATUS_NOT_IMPLEMENTED); - return SERVER_HANDLER_CONTINUE; + return SERVER_HANDLER_ABORT; } if (work->sess && conn->ops->is_sign_req(work, command)) { ret = conn->ops->check_sign_req(work); if (!ret) { conn->ops->set_rsp_status(work, STATUS_ACCESS_DENIED); - return SERVER_HANDLER_CONTINUE; + return SERVER_HANDLER_ABORT; } }