On Tue, Oct 24, 2023 at 09:09:54AM +0800, Maria Yu wrote:
> Module PLT feature can be enabled even when RANDOM_BASE is disabled.
> Break BLT entry counts of relocation types will make module plt entry
> allocation fail and finally exec format error for even correct and plt
> allocation available modules.
The patch itself looks good; it would be better if we could make the commit
message explicit that this is a fix. Could we please replace that with:
| arm64: module: fix PLT counting when CONFIG_RANDOMIZE_BASE=n
|
| The counting of module PLTs has been broken when CONFIG_RANDOMIZE_BASE=n
| since commit:
|
| 3e35d303ab7d22c4 ("arm64: module: rework module VA range selection")
|
| Prior to that commit, when CONFIG_RANDOMIZE_BASE=n, the kernel image and
| all modules were placed within a 128M region, and no PLTs were necessary
| for B or BL. Hence count_plts() and partition_branch_plt_relas() skipped
| handling B and BL when CONFIG_RANDOMIZE_BASE=n.
|
| After that commit, modules can be placed anywhere within a 2G window
| regardless of CONFIG_RANDOMIZE_BASE, and hence PLTs may be necessary for
| B and BL even when CONFIG_RANDOMIZE_BASE=n. Unfortunately that commit
| failed to update count_plts() and partition_branch_plt_relas()
| accordingly.
|
| Due to this, module_emit_plt_entry() may fail if an insufficient number
| of PLT entries have been reserved, resulting in modules failing to load
| with -ENOEXEC.
|
| Fix this by counting PLTs regardless of CONFIG_RANDOMIZE_BASE in
| count_plts() and partition_branch_plt_relas().
... and add a fixes tag:
Fixes: 3e35d303ab7d22c4 ("arm64: module: rework module VA range selection")
With that:
Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
Mark.
>
> Signed-off-by: Maria Yu <quic_aiquny@xxxxxxxxxxx>
> ---
> arch/arm64/kernel/module-plts.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c
> index bd69a4e7cd60..79200f21e123 100644
> --- a/arch/arm64/kernel/module-plts.c
> +++ b/arch/arm64/kernel/module-plts.c
> @@ -167,9 +167,6 @@ static unsigned int count_plts(Elf64_Sym *syms, Elf64_Rela *rela, int num,
> switch (ELF64_R_TYPE(rela[i].r_info)) {
> case R_AARCH64_JUMP26:
> case R_AARCH64_CALL26:
> - if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE))
> - break;
> -
> /*
> * We only have to consider branch targets that resolve
> * to symbols that are defined in a different section.
> @@ -269,9 +266,6 @@ static int partition_branch_plt_relas(Elf64_Sym *syms, Elf64_Rela *rela,
> {
> int i = 0, j = numrels - 1;
>
> - if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE))
> - return 0;
> -
> while (i < j) {
> if (branch_rela_needs_plt(syms, &rela[i], dstidx))
> i++;
>
> base-commit: 05d3ef8bba77c1b5f98d941d8b2d4aeab8118ef1
> --
> 2.17.1
>
