diff options
Diffstat (limited to 'arch/arm64/kernel/probes/uprobes.c')
| -rw-r--r-- | arch/arm64/kernel/probes/uprobes.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/arch/arm64/kernel/probes/uprobes.c b/arch/arm64/kernel/probes/uprobes.c index 1f91fd2a8187..2799bdb2fb82 100644 --- a/arch/arm64/kernel/probes/uprobes.c +++ b/arch/arm64/kernel/probes/uprobes.c @@ -6,6 +6,7 @@ #include <linux/ptrace.h> #include <linux/uprobes.h> #include <asm/cacheflush.h> +#include <asm/gcs.h> #include "decode-insn.h" @@ -159,11 +160,43 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs) { unsigned long orig_ret_vaddr; + unsigned long gcs_ret_vaddr; + int err = 0; + u64 gcspr; orig_ret_vaddr = procedure_link_pointer(regs); + + if (task_gcs_el0_enabled(current)) { + gcspr = read_sysreg_s(SYS_GCSPR_EL0); + gcs_ret_vaddr = get_user_gcs((__force unsigned long __user *)gcspr, &err); + if (err) { + force_sig(SIGSEGV); + goto out; + } + + /* + * If the LR and GCS return addr don't match, then some kind of PAC + * signing or control flow occurred since entering the probed function. + * Likely because the user is attempting to retprobe on an instruction + * that isn't a function boundary or inside a leaf function. Explicitly + * abort this retprobe because it will generate a GCS exception. + */ + if (gcs_ret_vaddr != orig_ret_vaddr) { + orig_ret_vaddr = -1; + goto out; + } + + put_user_gcs(trampoline_vaddr, (__force unsigned long __user *)gcspr, &err); + if (err) { + force_sig(SIGSEGV); + goto out; + } + } + /* Replace the return addr with trampoline addr */ procedure_link_pointer_set(regs, trampoline_vaddr); +out: return orig_ret_vaddr; } |