[PATCH] elf: _dl_fixup*: make @reloc_arg 64-bit safe

* [PATCH] elf: _dl_fixup*: make @reloc_arg 64-bit safe
@ 2021-07-22 13:22 Vladimir Isaev
  2021-07-22 13:39 ` Andreas Schwab
  0 siblings, 1 reply; 4+ messages in thread
From: Vladimir Isaev @ 2021-07-22 13:22 UTC (permalink / raw)
  To: libc-alpha
  Cc: linux-snps-arc, Vladimir Isaev, Cupertino Miranda, Vineet Gupta

This came up during arc64 glibc bringup on qemu usermode.

On ARC, lazy rezolver calls _dl_fixup() with 2nd argument as PC of the
PLT entry beiing fixed up. Thus this needs to be full 64-bit value for
arc64, however _dl_fixup() defines @reloc_arg as ElfW(Word) which maps
to Elf64_Word -> uint32_t causing gcc to truncate the value to 32-bits.

This problem show on 64-bit ARC and not other arches likely due to the
semantics of @reloc_arg. On ARC it is the runtime PC of PLT entry whereas for
others it might be the index or something similar which doesn't need
more than 32-bits.

Reported-by: Cupertino Miranda <cmiranda@synopsys.com>
Signed-off-by: Vladimir Isaev <isaev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 elf/dl-runtime.c          | 6 +++---
 sysdeps/hppa/dl-fptr.c    | 2 +-
 sysdeps/i386/dl-machine.h | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/elf/dl-runtime.c b/elf/dl-runtime.c
index 9d0d941000..6099a44ffb 100644
--- a/elf/dl-runtime.c
+++ b/elf/dl-runtime.c
@@ -56,7 +56,7 @@ _dl_fixup (
 # ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
 	   ELF_MACHINE_RUNTIME_FIXUP_ARGS,
 # endif
-	   struct link_map *l, ElfW(Word) reloc_arg)
+	   struct link_map *l, uintptr_t reloc_arg)
 {
   const ElfW(Sym) *const symtab
     = (const void *) D_PTR (l, l_info[DT_SYMTAB]);
@@ -152,7 +152,7 @@ _dl_profile_fixup (
 #ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
 		   ELF_MACHINE_RUNTIME_FIXUP_ARGS,
 #endif
-		   struct link_map *l, ElfW(Word) reloc_arg,
+		   struct link_map *l, uintptr_t reloc_arg,
 		   ElfW(Addr) retaddr, void *regs, long int *framesizep)
 {
   void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = _dl_mcount;
@@ -484,7 +484,7 @@ _dl_profile_fixup (
 #include <stdio.h>
 void
 ARCH_FIXUP_ATTRIBUTE
-_dl_call_pltexit (struct link_map *l, ElfW(Word) reloc_arg,
+_dl_call_pltexit (struct link_map *l, uintptr_t reloc_arg,
 		  const void *inregs, void *outregs)
 {
 #ifdef SHARED
diff --git a/sysdeps/hppa/dl-fptr.c b/sysdeps/hppa/dl-fptr.c
index 62ef68b62b..bcab1bf100 100644
--- a/sysdeps/hppa/dl-fptr.c
+++ b/sysdeps/hppa/dl-fptr.c
@@ -321,7 +321,7 @@ _dl_unmap (struct link_map *map)
   map->l_mach.fptr_table = NULL;
 }
 
-extern ElfW(Addr) _dl_fixup (struct link_map *, ElfW(Word)) attribute_hidden;
+extern ElfW(Addr) _dl_fixup (struct link_map *, uintptr_t) attribute_hidden;
 
 static inline Elf32_Addr
 elf_machine_resolve (void)
diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index 590b41d8d7..8f73e0efda 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -130,10 +130,10 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
 #define ARCH_FIXUP_ATTRIBUTE __attribute__ ((regparm (3), stdcall, unused))
 
 extern ElfW(Addr) _dl_fixup (struct link_map *l,
-			     ElfW(Word) reloc_offset)
+			     uintptr_t reloc_offset)
      ARCH_FIXUP_ATTRIBUTE;
 extern ElfW(Addr) _dl_profile_fixup (struct link_map *l,
-				     ElfW(Word) reloc_offset,
+				     uintptr_t reloc_offset,
 				     ElfW(Addr) retaddr, void *regs,
 				     long int *framesizep)
      ARCH_FIXUP_ATTRIBUTE;
-- 
2.32.0


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