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Alexei Starovoitov
96adbf7125
Andrii Nakryiko says:
====================
Fix global subprog PTR_TO_CTX arg handling
Fix confusing and incorrect inference of PTR_TO_CTX argument type in BPF
global subprogs. For some program types (iters, tracepoint, any program type
that doesn't have fixed named "canonical" context type) when user uses (in
a correct and valid way) a pointer argument to user-defined anonymous struct
type, verifier will incorrectly assume that it has to be PTR_TO_CTX argument.
While it should be just a PTR_TO_MEM argument with allowed size calculated
from user-provided (even if anonymous) struct.
This did come up in practice and was very confusing to users, so let's prevent
this going forward. We had to do a slight refactoring of
btf_get_prog_ctx_type() to make it easy to support a special s390x KPROBE use
cases. See details in respective patches.
v1->v2:
- special-case typedef bpf_user_pt_regs_t handling for KPROBE programs,
fixing s390x after changes in patch #2.
====================
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
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