https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=859c10beeeaaf1e0a1964118973aca1bc0460a51
commit 859c10beeeaaf1e0a1964118973aca1bc0460a51
Author: Corinna Vinschen <cori...@vinschen.de>
Date: Tue Aug 25 22:15:22 2015 +0200
autload.cc: Avoid clobbering return address in noload on i686
This fixes a long-standing problem when GetProcAddress fails
to load a function. The noload code calls SetLastError on
i686 without saving the edx register. Starting with Windows 7,
SetLastError apparently uses $edx and the register is set to
0x00000000 on return. So the subsequent `jmp *$edx' in noload
supposed to return to the caller, actually jumps to address NULL,
which results in a SEGV.
* autoload.cc (noload): i686 only: Save and restore $edx when
calling
SetLastError to avoid clobbering return address stating with
Windows 7.
Signed-off-by: Corinna Vinschen <cori...@vinschen.de>
Diff:
---
winsup/cygwin/ChangeLog | 5 +++++
winsup/cygwin/autoload.cc | 6 ++++--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index a23f835..c10d074 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,5 +1,10 @@
2015-08-25 Corinna Vinschen <cori...@vinschen.de>
+ * autoload.cc (noload): i686 only: Save and restore $edx when calling
+ SetLastError to avoid clobbering return address stating with Windows 7.
+
+2015-08-25 Corinna Vinschen <cori...@vinschen.de>
+
* mmap.cc: Fix a few comments.
2015-08-24 Corinna Vinschen <cori...@vinschen.de>
diff --git a/winsup/cygwin/autoload.cc b/winsup/cygwin/autoload.cc
index 4299e3a..8f9823b 100644
--- a/winsup/cygwin/autoload.cc
+++ b/winsup/cygwin/autoload.cc
@@ -254,11 +254,13 @@ noload:
\n\
addl %eax,%esp # Pop off bytes \n\
andl $0xffff0000,%eax# upper word \n\
subl %eax,%esp # adjust for possible return value \n\
- pushl %eax # Save for later \n\
+ pushl %eax # Save return value for later \n\
+ pushl %edx # Save return address for later \n\
movl $127,%eax # ERROR_PROC_NOT_FOUND \n\
pushl %eax # First argument \n\
call _SetLastError@4 # Set it \n\
- popl %eax # Get back argument \n\
+ popl %edx # Get back return address \n\
+ popl %eax # Get back return value \n\
sarl $16,%eax # return value in high order word \n\
jmp *%edx # Return \n\
1: \n\
