mirror of
https://github.com/torvalds/linux.git
synced 2026-08-17 12:59:51 +02:00
84f44df664
Similar to patch ("bpf: sock_ops ctx access may stomp registers") if the
src_reg = dst_reg when reading the sk field of a sock_ops struct we
generate xlated code,
53: (61) r9 = *(u32 *)(r9 +28)
54: (15) if r9 == 0x0 goto pc+3
56: (79) r9 = *(u64 *)(r9 +0)
This stomps on the r9 reg to do the sk_fullsock check and then when
reading the skops->sk field instead of the sk pointer we get the
sk_fullsock. To fix use similar pattern noted in the previous fix
and use the temp field to save/restore a register used to do
sk_fullsock check.
After the fix the generated xlated code reads,
52: (7b) *(u64 *)(r9 +32) = r8
53: (61) r8 = *(u32 *)(r9 +28)
54: (15) if r9 == 0x0 goto pc+3
55: (79) r8 = *(u64 *)(r9 +32)
56: (79) r9 = *(u64 *)(r9 +0)
57: (05) goto pc+1
58: (79) r8 = *(u64 *)(r9 +32)
Here r9 register was in-use so r8 is chosen as the temporary register.
In line 52 r8 is saved in temp variable and at line 54 restored in case
fullsock != 0. Finally we handle fullsock == 0 case by restoring at
line 58.
This adds a new macro SOCK_OPS_GET_SK it is almost possible to merge
this with SOCK_OPS_GET_FIELD, but I found the extra branch logic a
bit more confusing than just adding a new macro despite a bit of
duplicating code.
Fixes:
|
||
|---|---|---|
| .. | ||
| bpf_sk_storage.c | ||
| datagram.c | ||
| datagram.h | ||
| dev_addr_lists.c | ||
| dev_ioctl.c | ||
| dev.c | ||
| devlink.c | ||
| drop_monitor.c | ||
| dst_cache.c | ||
| dst.c | ||
| failover.c | ||
| fib_notifier.c | ||
| fib_rules.c | ||
| filter.c | ||
| flow_dissector.c | ||
| flow_offload.c | ||
| gen_estimator.c | ||
| gen_stats.c | ||
| gro_cells.c | ||
| hwbm.c | ||
| link_watch.c | ||
| lwt_bpf.c | ||
| lwtunnel.c | ||
| Makefile | ||
| neighbour.c | ||
| net_namespace.c | ||
| net-procfs.c | ||
| net-sysfs.c | ||
| net-sysfs.h | ||
| net-traces.c | ||
| netclassid_cgroup.c | ||
| netevent.c | ||
| netpoll.c | ||
| netprio_cgroup.c | ||
| page_pool.c | ||
| pktgen.c | ||
| ptp_classifier.c | ||
| request_sock.c | ||
| rtnetlink.c | ||
| scm.c | ||
| secure_seq.c | ||
| skbuff.c | ||
| skmsg.c | ||
| sock_diag.c | ||
| sock_map.c | ||
| sock_reuseport.c | ||
| sock.c | ||
| stream.c | ||
| sysctl_net_core.c | ||
| timestamping.c | ||
| tso.c | ||
| utils.c | ||
| xdp.c | ||