| Message ID | 20220327062202.5720-1-xiam0nd.tong@gmail.com |
|---|---|
| State | Accepted |
| Commit | 5ac11fe03a0a83042d1a040dbce4fa2fb5521e23 |
| Headers | show |
| Series | misc: fastrpc: fix an incorrect NULL check on list iterator | expand |
On 27/03/2022 07:22, Xiaomeng Tong wrote: > The bug is here: > if (!buf) { > > The list iterator value 'buf' will *always* be set and non-NULL > by list_for_each_entry(), so it is incorrect to assume that the > iterator value will be NULL if the list is empty (in this case, the > check 'if (!buf) {' will always be false and never exit expectly). > > To fix the bug, use a new variable 'iter' as the list iterator, > while use the original variable 'buf' as a dedicated pointer to > point to the found element. > > Cc: stable@vger.kernel.org > Fixes: 2419e55e532de ("misc: fastrpc: add mmap/unmap support") > Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> LGTM, Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > --- > drivers/misc/fastrpc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index aa1682b94a23..45aaf54a7560 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -1353,17 +1353,18 @@ static int fastrpc_req_munmap_impl(struct fastrpc_user *fl, > struct fastrpc_req_munmap *req) > { > struct fastrpc_invoke_args args[1] = { [0] = { 0 } }; > - struct fastrpc_buf *buf, *b; > + struct fastrpc_buf *buf = NULL, *iter, *b; > struct fastrpc_munmap_req_msg req_msg; > struct device *dev = fl->sctx->dev; > int err; > u32 sc; > > spin_lock(&fl->lock); > - list_for_each_entry_safe(buf, b, &fl->mmaps, node) { > - if ((buf->raddr == req->vaddrout) && (buf->size == req->size)) > + list_for_each_entry_safe(iter, b, &fl->mmaps, node) { > + if ((iter->raddr == req->vaddrout) && (iter->size == req->size)) { > + buf = iter; > break; > - buf = NULL; > + } > } > spin_unlock(&fl->lock); >
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index aa1682b94a23..45aaf54a7560 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -1353,17 +1353,18 @@ static int fastrpc_req_munmap_impl(struct fastrpc_user *fl, struct fastrpc_req_munmap *req) { struct fastrpc_invoke_args args[1] = { [0] = { 0 } }; - struct fastrpc_buf *buf, *b; + struct fastrpc_buf *buf = NULL, *iter, *b; struct fastrpc_munmap_req_msg req_msg; struct device *dev = fl->sctx->dev; int err; u32 sc; spin_lock(&fl->lock); - list_for_each_entry_safe(buf, b, &fl->mmaps, node) { - if ((buf->raddr == req->vaddrout) && (buf->size == req->size)) + list_for_each_entry_safe(iter, b, &fl->mmaps, node) { + if ((iter->raddr == req->vaddrout) && (iter->size == req->size)) { + buf = iter; break; - buf = NULL; + } } spin_unlock(&fl->lock);
The bug is here: if (!buf) { The list iterator value 'buf' will *always* be set and non-NULL by list_for_each_entry(), so it is incorrect to assume that the iterator value will be NULL if the list is empty (in this case, the check 'if (!buf) {' will always be false and never exit expectly). To fix the bug, use a new variable 'iter' as the list iterator, while use the original variable 'buf' as a dedicated pointer to point to the found element. Cc: stable@vger.kernel.org Fixes: 2419e55e532de ("misc: fastrpc: add mmap/unmap support") Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> --- drivers/misc/fastrpc.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)