From: Dan Carpenter dan.carpenter@linaro.org
commit fa332f5dc6fc662ad7d3200048772c96b861cf6b upstream
The "intf" list iterator is an invalid pointer if the correct "intf->intf_num" is not found. Calling atomic_dec(&intf->nr_users) on and invalid pointer will lead to memory corruption.
We don't really need to call atomic_dec() if we haven't called atomic_add_return() so update the if (intf->in_shutdown) path as well.
Fixes: 8e76741c3d8b ("ipmi: Add a limit on the number of users that may use IPMI") Signed-off-by: Dan Carpenter dan.carpenter@linaro.org Message-ID: aBjMZ8RYrOt6NOgi@stanley.mountain Signed-off-by: Corey Minyard corey@minyard.net Signed-off-by: Brendan Jackman jackmanb@google.com --- I have tested this in 6.12 with Google's platform drivers added to reproduce the bug. The bug causes the panic notifier chain to get corrupted leading to a crash. With the fix this goes away.
Applies to 6.6 too but I haven't tested it there.
Backport changes:
- Dropped change to the `if (intf->in_shutdown)` block since that logic doesn't exist yet. - Modified out_unlock to release the srcu lock instead of the mutex since we don't have the mutex here yet. --- drivers/char/ipmi/ipmi_msghandler.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c index e12b531f5c2f338008a42dc2c35b0a62395c9f3c..6a4a8ecd0edd02793eda70f9f9ae578e37da477f 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -1241,7 +1241,7 @@ int ipmi_create_user(unsigned int if_num, } /* Not found, return an error */ rv = -EINVAL; - goto out_kfree; + goto out_unlock;
found: if (atomic_add_return(1, &intf->nr_users) > max_users) { @@ -1283,6 +1283,7 @@ int ipmi_create_user(unsigned int if_num,
out_kfree: atomic_dec(&intf->nr_users); +out_unlock: srcu_read_unlock(&ipmi_interfaces_srcu, index); vfree(new_user); return rv;
--- base-commit: 783cd2c3dca8b6c434e955b84c20c8940588dc68 change-id: 20250630-ipmi-fix-c565f7098afd
Best regards,