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arm64: Fail module loading if dynamic SCS patching fails

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Disallow a module to load if SCS dynamic patching fails for its code. For
module loading, instead of running a dry-run to check for patching errors,
try to run patching in the first run and propagate any errors so module
loading will fail.

Signed-off-by: Adrian Barnaś <abarnas@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Adrian Barnaś
2025-09-22 13:04:26 +00:00
committed by Will Deacon
parent 7f16357378
commit 6d4a0fbd34
5 changed files with 19 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm64/include/asm/scs.h
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@@ -53,7 +53,7 @@ enum {
EDYNSCS_INVALID_CFA_OPCODE = 4,
};
int __pi_scs_patch(const u8 eh_frame[], int size);
int __pi_scs_patch(const u8 eh_frame[], int size, bool skip_dry_run);
#endif /* __ASSEMBLY __ */

12
arch/arm64/kernel/module.c
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@@ -495,10 +495,18 @@ int module_finalize(const Elf_Ehdr *hdr,
if (scs_is_dynamic()) {
s = find_section(hdr, sechdrs, ".init.eh_frame");
if (s) {
ret = __pi_scs_patch((void *)s->sh_addr, s->sh_size);
if (ret)
/*
* Because we can reject modules that are malformed
* so SCS patching fails, skip dry run and try to patch
* it in place. If patching fails, the module would not
* be loaded anyway.
*/
ret = __pi_scs_patch((void *)s->sh_addr, s->sh_size, true);
if (ret) {
pr_err("module %s: error occurred during dynamic SCS patching (%d)\n",
me->name, ret);
return -ENOEXEC;
}
}
}

2
arch/arm64/kernel/pi/map_kernel.c
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@@ -104,7 +104,7 @@ static void __init map_kernel(u64 kaslr_offset, u64 va_offset, int root_level)
if (enable_scs) {
scs_patch(__eh_frame_start + va_offset,
__eh_frame_end - __eh_frame_start);
__eh_frame_end - __eh_frame_start, false);
asm("ic ialluis");
dynamic_scs_is_enabled = true;

10
arch/arm64/kernel/pi/patch-scs.c
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@@ -225,7 +225,7 @@ static int scs_handle_fde_frame(const struct eh_frame *frame,
return 0;
}
int scs_patch(const u8 eh_frame[], int size)
int scs_patch(const u8 eh_frame[], int size, bool skip_dry_run)
{
int code_alignment_factor = 1;
bool fde_use_sdata8 = false;
@@ -277,11 +277,13 @@ int scs_patch(const u8 eh_frame[], int size)
}
} else {
ret = scs_handle_fde_frame(frame, code_alignment_factor,
fde_use_sdata8, true);
fde_use_sdata8, !skip_dry_run);
if (ret)
return ret;
scs_handle_fde_frame(frame, code_alignment_factor,
fde_use_sdata8, false);
if (!skip_dry_run)
scs_handle_fde_frame(frame, code_alignment_factor,
fde_use_sdata8, false);
}
p += sizeof(frame->size) + frame->size;

2
arch/arm64/kernel/pi/pi.h
View File

@@ -27,7 +27,7 @@ extern pgd_t init_pg_dir[], init_pg_end[];
void init_feature_override(u64 boot_status, const void *fdt, int chosen);
u64 kaslr_early_init(void *fdt, int chosen);
void relocate_kernel(u64 offset);
int scs_patch(const u8 eh_frame[], int size);
int scs_patch(const u8 eh_frame[], int size, bool skip_dry_run);
void map_range(phys_addr_t *pte, u64 start, u64 end, phys_addr_t pa,
pgprot_t prot, int level, pte_t *tbl, bool may_use_cont,