Re: [PATCH bpf-next v3] bpftool: Fix gen object segfault

[Quentin Monnet]

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>

Thank you!