From 368ae537e056acd3f751fa276f48423f06803922 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Svenning=20S=C3=B8rensen?= Date: Wed, 28 Aug 2013 16:35:17 -0700 Subject: [PATCH] IPC: bugfix for msgrcv with msgtyp < 0 According to 'man msgrcv': "If msgtyp is less than 0, the first message of the lowest type that is less than or equal to the absolute value of msgtyp shall be received." Bug: The kernel only returns a message if its type is 1; other messages with type < abs(msgtype) will never get returned. Fix: After having traversed the list to find the first message with the lowest type, we need to actually return that message. This regression was introduced by commit daaf74cf0867 ("ipc: refactor msg list search into separate function") Signed-off-by: Svenning Soerensen Reviewed-by: Peter Hurley Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/msg.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/ipc/msg.c b/ipc/msg.c index bd60d7e159e8..9f29d9e89bac 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -839,7 +839,7 @@ static inline void free_copy(struct msg_msg *copy) static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) { - struct msg_msg *msg; + struct msg_msg *msg, *found = NULL; long count = 0; list_for_each_entry(msg, &msq->q_messages, m_list) { @@ -848,6 +848,7 @@ static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) *msgtyp, mode)) { if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { *msgtyp = msg->m_type - 1; + found = msg; } else if (mode == SEARCH_NUMBER) { if (*msgtyp == count) return msg; @@ -857,7 +858,7 @@ static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) } } - return ERR_PTR(-EAGAIN); + return found ?: ERR_PTR(-EAGAIN); } long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg, -- 2.30.2