x86/a.out: Clear the dump structure initially

suryasaimadhu · suryasaimadhu · commit 10970e1b4be9 · 2019-02-13T12:10:51.000+01:00
dump_thread32() in aout_core_dump() does not clear the user32 structure allocated on the stack as the first thing on function entry. As a result, the dump.u_comm, dump.u_ar0 and dump.signal which get assigned before the clearing, get overwritten. Rename that function to fill_dump() to make it clear what it does and call it first thing. This was caught while staring at a patch by Derek Robson <robsonde@gmail.com>. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Derek Robson <robsonde@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Matz <matz@suse.de> Cc: x86@kernel.org Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20190202005512.3144-1-robsonde@gmail.com
diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
@@ -51,7 +51,7 @@ static unsigned long get_dr(int n)
 /*
  * fill in the user structure for a core dump..
  */
-static void dump_thread32(struct pt_regs *regs, struct user32 *dump)
+static void fill_dump(struct pt_regs *regs, struct user32 *dump)
 {
 	u32 fs, gs;
 	memset(dump, 0, sizeof(*dump));
@@ -157,10 +157,12 @@ static int aout_core_dump(struct coredump_params *cprm)
 	fs = get_fs();
 	set_fs(KERNEL_DS);
 	has_dumped = 1;
+
+	fill_dump(cprm->regs, &dump);
+
 	strncpy(dump.u_comm, current->comm, sizeof(current->comm));
 	dump.u_ar0 = offsetof(struct user32, regs);
 	dump.signal = cprm->siginfo->si_signo;
-	dump_thread32(cprm->regs, &dump);
 
 	/*
 	 * If the size of the dump file exceeds the rlimit, then see
