6.12-stable review patch. If anyone has any objections, please let me know.
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From: Guenter Roeck linux@roeck-us.net
commit e2c69490dda5d4c9f1bfbb2898989c8f3530e354 upstream
Prior to commit b52da4054ee0 ("ipmi: Rework user message limit handling"), i_ipmi_request() used to increase the user reference counter if the receive message is provided by the caller of IPMI API functions. This is no longer the case. However, ipmi_free_recv_msg() is still called and decreases the reference counter. This results in the reference counter reaching zero, the user data pointer is released, and all kinds of interesting crashes are seen.
Fix the problem by increasing user reference counter if the receive message has been provided by the caller.
Fixes: b52da4054ee0 ("ipmi: Rework user message limit handling") Reported-by: Eric Dumazet edumazet@google.com Cc: Eric Dumazet edumazet@google.com Cc: Greg Thelen gthelen@google.com Signed-off-by: Guenter Roeck linux@roeck-us.net Message-ID: 20251006201857.3433837-1-linux@roeck-us.net Signed-off-by: Corey Minyard corey@minyard.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/ipmi/ipmi_msghandler.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -2311,8 +2311,11 @@ static int i_ipmi_request(struct ipmi_us if (supplied_recv) { recv_msg = supplied_recv; recv_msg->user = user; - if (user) + if (user) { atomic_inc(&user->nr_msgs); + /* The put happens when the message is freed. */ + kref_get(&user->refcount); + } } else { recv_msg = ipmi_alloc_recv_msg(user); if (IS_ERR(recv_msg))