From 203e4f42596ede31498744018716a3db6dbb7f51 Mon Sep 17 00:00:00 2001 From: Takamitsu Iwai Date: Sat, 23 Aug 2025 17:58:56 +0900 Subject: net: rose: convert 'use' field to refcount_t [ Upstream commit d860d1faa6b2ce3becfdb8b0c2b048ad31800061 ] The 'use' field in struct rose_neigh is used as a reference counter but lacks atomicity. This can lead to race conditions where a rose_neigh structure is freed while still being referenced by other code paths. For example, when rose_neigh->use becomes zero during an ioctl operation via rose_rt_ioctl(), the structure may be removed while its timer is still active, potentially causing use-after-free issues. This patch changes the type of 'use' from unsigned short to refcount_t and updates all code paths to use rose_neigh_hold() and rose_neigh_put() which operate reference counts atomically. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Takamitsu Iwai Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250823085857.47674-3-takamitz@amazon.co.jp Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/rose.h | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/net/rose.h b/include/net/rose.h index 174b4f605d84..2b5491bbf39a 100644 --- a/include/net/rose.h +++ b/include/net/rose.h @@ -8,6 +8,7 @@ #ifndef _ROSE_H #define _ROSE_H +#include #include #include #include @@ -96,7 +97,7 @@ struct rose_neigh { ax25_cb *ax25; struct net_device *dev; unsigned short count; - unsigned short use; + refcount_t use; unsigned int number; char restarted; char dce_mode; @@ -151,12 +152,19 @@ struct rose_sock { #define rose_sk(sk) ((struct rose_sock *)(sk)) +static inline void rose_neigh_hold(struct rose_neigh *rose_neigh) +{ + refcount_inc(&rose_neigh->use); +} + static inline void rose_neigh_put(struct rose_neigh *rose_neigh) { - if (rose_neigh->ax25) - ax25_cb_put(rose_neigh->ax25); - kfree(rose_neigh->digipeat); - kfree(rose_neigh); + if (refcount_dec_and_test(&rose_neigh->use)) { + if (rose_neigh->ax25) + ax25_cb_put(rose_neigh->ax25); + kfree(rose_neigh->digipeat); + kfree(rose_neigh); + } } /* af_rose.c */ -- cgit v1.2.3