From: Linus Torvalds torvalds@linux-foundation.org
mainline inclusion from mainline-v6.11-rc2 commit b6547e54864b998af21fdcaa0a88cf8e7efe641a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB2BWT CVE: CVE-2024-50102
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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The runtime constants linker script depended on documented linker behavior [1]:
"If an output section’s name is the same as the input section’s name and is representable as a C identifier, then the linker will automatically PROVIDE two symbols: __start_SECNAME and __stop_SECNAME, where SECNAME is the name of the section. These indicate the start address and end address of the output section respectively"
to just automatically define the symbol names for the bounds of the runtime constant arrays.
It turns out that this isn't actually something we can rely on, with old linkers not generating these automatic symbols. It looks to have been introduced in binutils-2.29 back in 2017, and we still support building with versions all the way back to binutils-2.25 (from 2015).
And yes, Oleg actually seems to be using such ancient versions of binutils.
So instead of depending on the implicit symbols from "section names match and are representable C identifiers", just do this all manually. It's not like it causes us any extra pain, we already have to do that for all the other sections that we use that often have special characters in them.
Reported-and-tested-by: Oleg Nesterov oleg@redhat.com Link: https://sourceware.org/binutils/docs/ld/Input-Section-Example.html [1] Link: https://lore.kernel.org/all/20240802114518.GA20924@redhat.com/ Signed-off-by: Linus Torvalds torvalds@linux-foundation.org
Conflicts: include/asm-generic/vmlinux.lds.h [Context conflicts] Signed-off-by: Qi Xi xiqi2@huawei.com --- include/asm-generic/vmlinux.lds.h | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 174d865ce46e..afcc180910c6 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -954,6 +954,13 @@ #define CON_INITCALL \ BOUNDED_SECTION_POST_LABEL(.con_initcall.init, __con_initcall, _start, _end)
+#define NAMED_SECTION(name) \ + . = ALIGN(8); \ + name : AT(ADDR(name) - LOAD_OFFSET) \ + { BOUNDED_SECTION_PRE_LABEL(name, name, __start_, __stop_) } + +#define RUNTIME_CONST(t,x) NAMED_SECTION(runtime_##t##_##x) + /* Alignment must be consistent with (kunit_suite *) in include/kunit/test.h */ #define KUNIT_TABLE() \ . = ALIGN(8); \