diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2025-06-10 18:33:28 +0200 |
|---|---|---|
| committer | Daniel Gomez <da.gomez@samsung.com> | 2025-07-08 20:52:30 +0200 |
| commit | 570db4b39f535a8bb722adb8be0280d09e34ca99 (patch) | |
| tree | 67412e8605e19f9f70267f7e71d093f06638ebeb | |
| parent | eb0994a954978f0edd3efb38d0cbe6744df8b83d (diff) | |
module: Make sure relocations are applied to the per-CPU section
The per-CPU data section is handled differently than the other sections.
The memory allocations requires a special __percpu pointer and then the
section is copied into the view of each CPU. Therefore the SHF_ALLOC
flag is removed to ensure move_module() skips it.
Later, relocations are applied and apply_relocations() skips sections
without SHF_ALLOC because they have not been copied. This also skips the
per-CPU data section.
The missing relocations result in a NULL pointer on x86-64 and very
small values on x86-32. This results in a crash because it is not
skipped like NULL pointer would and can't be dereferenced.
Such an assignment happens during static per-CPU lock initialisation
with lockdep enabled.
Allow relocation processing for the per-CPU section even if SHF_ALLOC is
missing.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202506041623.e45e4f7d-lkp@intel.com
Fixes: 1a6100caae425 ("Don't relocate non-allocated regions in modules.") #v2.6.1-rc3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
Link: https://lore.kernel.org/r/20250610163328.URcsSUC1@linutronix.de
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Message-ID: <20250610163328.URcsSUC1@linutronix.de>
| -rw-r--r-- | kernel/module/main.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/module/main.c b/kernel/module/main.c index 7822b91fca6b..c2c08007029d 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1573,8 +1573,14 @@ static int apply_relocations(struct module *mod, const struct load_info *info) if (infosec >= info->hdr->e_shnum) continue; - /* Don't bother with non-allocated sections */ - if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC)) + /* + * Don't bother with non-allocated sections. + * An exception is the percpu section, which has separate allocations + * for individual CPUs. We relocate the percpu section in the initial + * ELF template and subsequently copy it to the per-CPU destinations. + */ + if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC) && + (!infosec || infosec != info->index.pcpu)) continue; if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH) |