| Message ID | 20220902131344.3029826-2-abel.vesa@linaro.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | misc: fastrpc: Add audiopd support and some fixes | expand |
On 22-09-02 15:25:10, Greg Kroah-Hartman wrote: > On Fri, Sep 02, 2022 at 04:13:31PM +0300, Abel Vesa wrote: > > Currently, there is a race window between the point when the mutex is > > unlocked in fastrpc_map_lookup and the reference count increasing > > (fastrpc_map_get) in fastrpc_map_find, which can also lead to > > use-after-free. > > > > So lets merge fastrpc_map_find into fastrpc_map_lookup which allows us > > to both protect the maps list by also taking the &fl->lock spinlock and > > the reference count, since the spinlock will be released only after. > > Add take_ref argument to make this suitable for all callers. > > > > Co-developed-by: Ola Jeppsson <ola@snap.com> > > Signed-off-by: Ola Jeppsson <ola@snap.com> > > Signed-off-by: Abel Vesa <abel.vesa@linaro.org> > > --- > > drivers/misc/fastrpc.c | 41 +++++++++++++++++++++-------------------- > > 1 file changed, 21 insertions(+), 20 deletions(-) > > What commit does this fix? Should it go to stable trees? Will specify in the next version. > > Try splitting this series up into 2, one for 6.0-final with bugfixes to > resolve issues found, and the next one on top of that for new features. Fair point. Will do in the next version. > > thanks, > > greg k-h
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 93ebd174d848..0c816a11eeec 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -333,30 +333,31 @@ static void fastrpc_map_get(struct fastrpc_map *map) static int fastrpc_map_lookup(struct fastrpc_user *fl, int fd, - struct fastrpc_map **ppmap) + struct fastrpc_map **ppmap, bool take_ref) { + struct fastrpc_session_ctx *sess = fl->sctx; struct fastrpc_map *map = NULL; + int ret = -ENOENT; - mutex_lock(&fl->mutex); + spin_lock(&fl->lock); list_for_each_entry(map, &fl->maps, node) { - if (map->fd == fd) { - *ppmap = map; - mutex_unlock(&fl->mutex); - return 0; - } - } - mutex_unlock(&fl->mutex); - - return -ENOENT; -} + if (map->fd != fd) + continue; -static int fastrpc_map_find(struct fastrpc_user *fl, int fd, - struct fastrpc_map **ppmap) -{ - int ret = fastrpc_map_lookup(fl, fd, ppmap); + if (take_ref) { + ret = fastrpc_map_get(map); + if (ret) { + dev_dbg(sess->dev, "%s: Failed to get map fd=%d ret=%d\n", + __func__, fd, ret); + break; + } + } - if (!ret) - fastrpc_map_get(*ppmap); + *ppmap = map; + ret = 0; + break; + } + spin_unlock(&fl->lock); return ret; } @@ -703,7 +704,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd, struct fastrpc_map *map = NULL; int err = 0; - if (!fastrpc_map_find(fl, fd, ppmap)) + if (!fastrpc_map_lookup(fl, fd, ppmap, true)) return 0; map = kzalloc(sizeof(*map), GFP_KERNEL); @@ -1026,7 +1027,7 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx, for (i = 0; i < FASTRPC_MAX_FDLIST; i++) { if (!fdlist[i]) break; - if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap)) + if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap, false)) fastrpc_map_put(mmap); }