On Tue, Feb 11, 2025 at 8:48 AM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Tue, Feb 11, 2025 at 3:16 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > > > Jann reported [1] possible issue when trampoline_check_ip returns > > address near the bottom of the address space that is allowed to > > call into the syscall if uretprobes are not set up. > > > > Though the mmap minimum address restrictions will typically prevent > > creating mappings there, let's make sure uretprobe syscall checks > > for that. > > > > [1] https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf > > Cc: Kees Cook <kees@xxxxxxxxxx> > > Cc: Eyal Birger <eyal.birger@xxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > Fixes: ff474a78cef5 ("uprobe: Add uretprobe syscall to speed up return probe") > > Reported-by: Jann Horn <jannh@xxxxxxxxxx> > > Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx> > > Reviewed-by: Kees Cook <kees@xxxxxxxxxx> > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> > > --- > > v2 changes: > > - adding UPROBE_NO_TRAMPOLINE_VADDR macro (Andrii) > > - rebased on top of perf/core > > > > arch/x86/kernel/uprobes.c | 16 +++++++++++----- > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c > > index 5a952c5ea66b..e8d3c59aa9f7 100644 > > --- a/arch/x86/kernel/uprobes.c > > +++ b/arch/x86/kernel/uprobes.c > > @@ -357,19 +357,25 @@ void *arch_uprobe_trampoline(unsigned long *psize) > > return &insn; > > } > > > > -static unsigned long trampoline_check_ip(void) > > +static unsigned long trampoline_check_ip(unsigned long tramp) > > { > > - unsigned long tramp = uprobe_get_trampoline_vaddr(); > > - > > return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry); > > } > > > > +#define UPROBE_NO_TRAMPOLINE_VADDR ((unsigned long)-1) If you respin anyway maybe use ~0UL instead? In the above and in uprobe_get_trampoline_vaddr(), since unsigned long trampoline_vaddr = -1; looks odd too.
