On Thu, Dec 5, 2024 at 4:22 AM Quentin Monnet <qmo@xxxxxxxxxx> wrote: > > On 05/12/2024 12:09, Rong Tao wrote: > > From: Rong Tao <rongtao@xxxxxxxx> > > > > If the input file and output file are the same, the input file is cleared > > due to opening, resulting in a NULL pointer access by libbpf. > > > > $ bpftool gen object prog.o prog.o > > libbpf: failed to get ELF header for prog.o: invalid `Elf' handle > > Segmentation fault > > > > (gdb) bt > > #0 0x0000000000450285 in linker_append_elf_syms (linker=0x4feda0, obj=0x7fffffffe100) at linker.c:1296 > > #1 bpf_linker__add_file (linker=0x4feda0, filename=<optimized out>, opts=<optimized out>) at linker.c:453 > > #2 0x000000000040c235 in do_object () > > #3 0x00000000004021d7 in main () > > (gdb) frame 0 > > #0 0x0000000000450285 in linker_append_elf_syms (linker=0x4feda0, obj=0x7fffffffe100) at linker.c:1296 > > 1296 Elf64_Sym *sym = symtab->data->d_buf; > > > > Signed-off-by: Rong Tao <rongtao@xxxxxxxx> > > Tested-by: Quentin Monnet <qmo@xxxxxxxxxx> > Reviewed-by: Quentin Monnet <qmo@xxxxxxxxxx> Isn't this papering over a deeper underlying issue? Why do we get SIGSEGV inside the linker at all instead of just erroring out? Comparison based on file path isn't a reliable way to check if input and output are both the same file, so this fixes the most obvious case, but not the actual issue. > > Thank you!
