| Message ID | 1608793298-123684-1-git-send-email-abaci-bugfix@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf: fix: address of local auto-variable assigned to a function parameter. | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On 12/23/20 11:01 PM, YANG LI wrote: > Assigning local variable txq to the outputting parameter xdp->txq is not > safe, txq will be released after the end of the function call. > Then the result of using xdp is unpredictable. > > Fix this error by defining the struct xdp_txq_info in function > dev_map_run_prog() as a static type. > > Signed-off-by: YANG LI <abaci-bugfix@linux.alibaba.com> > Reported-by: Abaci <abaci@linux.alibaba.com> > --- > kernel/bpf/devmap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c > index f6e9c68..af6f004 100644 > --- a/kernel/bpf/devmap.c > +++ b/kernel/bpf/devmap.c > @@ -454,7 +454,7 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev, > struct xdp_buff *xdp, > struct bpf_prog *xdp_prog) > { > - struct xdp_txq_info txq = { .dev = dev }; > + static struct xdp_txq_info txq = { .dev = dev }; > u32 act; > > xdp_set_data_meta_invalid(xdp); exposing txq outside the routine with 'static' definition is not a good practice. maybe just reset xdp->txq = NULl right before function return? diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index f6e9c68afdd4..50f5c20a33a3 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -475,6 +475,7 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev, } xdp_return_buff(xdp); + xdp->txq = NULL; return NULL; } -bash-4.4$
On 12/24/20 12:01 AM, YANG LI wrote: > Assigning local variable txq to the outputting parameter xdp->txq is not > safe, txq will be released after the end of the function call. > Then the result of using xdp is unpredictable. txq can only be accessed in this devmap context. Was it actually hit during runtime or is this report based on code analysis? > > Fix this error by defining the struct xdp_txq_info in function > dev_map_run_prog() as a static type. > > Signed-off-by: YANG LI <abaci-bugfix@linux.alibaba.com> > Reported-by: Abaci <abaci@linux.alibaba.com> > --- > kernel/bpf/devmap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c > index f6e9c68..af6f004 100644 > --- a/kernel/bpf/devmap.c > +++ b/kernel/bpf/devmap.c > @@ -454,7 +454,7 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev, > struct xdp_buff *xdp, > struct bpf_prog *xdp_prog) > { > - struct xdp_txq_info txq = { .dev = dev }; > + static struct xdp_txq_info txq = { .dev = dev }; > u32 act; > > xdp_set_data_meta_invalid(xdp); >
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index f6e9c68..af6f004 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -454,7 +454,7 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev, struct xdp_buff *xdp, struct bpf_prog *xdp_prog) { - struct xdp_txq_info txq = { .dev = dev }; + static struct xdp_txq_info txq = { .dev = dev }; u32 act; xdp_set_data_meta_invalid(xdp);
Assigning local variable txq to the outputting parameter xdp->txq is not safe, txq will be released after the end of the function call. Then the result of using xdp is unpredictable. Fix this error by defining the struct xdp_txq_info in function dev_map_run_prog() as a static type. Signed-off-by: YANG LI <abaci-bugfix@linux.alibaba.com> Reported-by: Abaci <abaci@linux.alibaba.com> --- kernel/bpf/devmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)