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[1/4] ELF/BFD: Fix padding in `elf_external_linux_prpsinfo64'

Message ID alpine.DEB.2.00.1709221409510.16752@tp.orcam.me.uk
State Committed
Headers show

Commit Message

Maciej W. Rozycki Sept. 23, 2017, 12:03 a.m. UTC
Fix commit 70a38d42c5b3 ("New entry points for writing Linux NT_PRPSINFO 
notes."), <https://sourceware.org/ml/binutils/2013-02/msg00023.html>, 
and move the padding of the `elf_external_linux_prpsinfo64' structure to 
match the corresponding 64-bit Linux kernel `elf_prpsinfo' structure.

The 64-bit kernel structure is defined as follows:

(gdb) ptype struct elf_prpsinfo
type = struct elf_prpsinfo {
    char pr_state;
    char pr_sname;
    char pr_zomb;
    char pr_nice;
    unsigned long pr_flag;
    __kernel_uid_t pr_uid;
    __kernel_gid_t pr_gid;
    pid_t pr_pid;
    pid_t pr_ppid;
    pid_t pr_pgrp;
    pid_t pr_sid;
    char pr_fname[16];
    char pr_psargs[80];
}
(gdb) print /x &((struct elf_prpsinfo *)0)->pr_nice
$1 = 0x3
(gdb) print /x &((struct elf_prpsinfo *)0)->pr_flag
$2 = 0x8
(gdb) print /x &((struct elf_prpsinfo *)0)->pr_uid
$3 = 0x10
(gdb) print sizeof(((struct elf_prpsinfo *)0)->pr_flag)
$4 = 8
(gdb)

with implicit padding present before the `pr_flag' member, to correctly 
align it to a multiple of 8.  Conversely `elf_external_linux_prpsinfo64' 
has padding after its `pr_flag' member:

(top-gdb) ptype struct elf_external_linux_prpsinfo64
type = struct elf_external_linux_prpsinfo64 {
    char pr_state;
    char pr_sname;
    char pr_zomb;
    char pr_nice;
    char pr_flag[8];
    char gap[4];
    char pr_uid[4];
    char pr_gid[4];
    char pr_pid[4];
    char pr_ppid[4];
    char pr_pgrp[4];
    char pr_sid[4];
    char pr_fname[16];
    char pr_psargs[80];
}
(top-gdb) print /x &((struct elf_external_linux_prpsinfo64 *)0)->pr_nice
$1 = 0x3
(top-gdb) print /x &((struct elf_external_linux_prpsinfo64 *)0)->pr_flag
$2 = 0x4
(top-gdb) print /x &((struct elf_external_linux_prpsinfo64 *)0)->pr_uid
$3 = 0x10
(top-gdb)

and consequently `pr_flag' is misplaced.  Move `gap' ahead of `pr_flag'
then.

	bfd/
	* elf-linux-core.h (elf_external_linux_prpsinfo64): Move the 
	`gap' member ahead of `pr_flag'.
---
 bfd/elf-linux-core.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

Index: binutils/bfd/elf-linux-core.h
===================================================================
--- binutils.orig/bfd/elf-linux-core.h	2017-07-31 09:18:48.000000000 +0100
+++ binutils/bfd/elf-linux-core.h	2017-09-19 15:49:09.859093825 +0100
@@ -85,8 +85,8 @@  struct elf_external_linux_prpsinfo64
     char pr_sname;			/* Char for pr_state.  */
     char pr_zomb;			/* Zombie.  */
     char pr_nice;			/* Nice val.  */
-    char pr_flag[8];			/* Flags.  */
     char gap[4];
+    char pr_flag[8];			/* Flags.  */
     char pr_uid[4];
     char pr_gid[4];
     char pr_pid[4];