Re: [PATCH] bpf: fix: address of local auto-variable assigned to a function parameter.
From: David Ahern <hidden>
Date: 2020-12-25 00:50:58
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bpf, lkml
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?
quoted hunk ↗ jump to hunk
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 <redacted> Reported-by: Abaci <redacted> --- 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);