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fix(driver/modern_bpf): read signal_deliver siginfo via BPF_CORE_READ #3119

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Merged
poiana merged 1 commit into from
Sep 28, 2026
Merged

fix(driver/modern_bpf): read signal_deliver siginfo via BPF_CORE_READ #3119

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15 changes: 10 additions & 5 deletions driver/modern_bpf/programs/attached/events/signal_deliver.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,29 +30,34 @@ int BPF_PROG(signal_deliver, int sig, struct kernel_siginfo *info, struct k_siga
/* Try to find the source pid */
pid_t spid = 0;

/* Signal tracepoints can receive the `SEND_SIG_NOINFO` (0) and
* `SEND_SIG_PRIV` (1) sentinels instead of a real pointer, so newer kernels
* expose `info` as a scalar and the verifier rejects direct accesses.
* `BPF_CORE_READ` works with both the scalar and the BTF pointer.
*/
if(info != NULL) {
switch(sig) {
case SIGKILL:
spid = info->_sifields._kill._pid;
spid = BPF_CORE_READ(info, _sifields._kill._pid);
break;

case SIGTERM:
case SIGHUP:
case SIGINT:
case SIGTSTP:
case SIGQUIT: {
int si_code = info->si_code;
int si_code = BPF_CORE_READ(info, si_code);
if(si_code == SI_USER || si_code == SI_QUEUE || si_code <= 0) {
/* This is equivalent to `info->si_pid` where
* `si_pid` is a macro `_sifields._kill._pid`
*/
spid = info->_sifields._kill._pid;
spid = BPF_CORE_READ(info, _sifields._kill._pid);
}
break;
}

case SIGCHLD:
spid = info->_sifields._sigchld._pid;
spid = BPF_CORE_READ(info, _sifields._sigchld._pid);
break;

default:
Expand All @@ -61,7 +66,7 @@ int BPF_PROG(signal_deliver, int sig, struct kernel_siginfo *info, struct k_siga
}

if(sig >= SIGRTMIN && sig <= SIGRTMAX) {
spid = info->_sifields._rt._pid;
spid = BPF_CORE_READ(info, _sifields._rt._pid);
}
}

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