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Re: [PATCH PR gdb/15236] gdbserver write to linux memory with zero length corrupts stack
- From: Jeremy Bennett <jeremy dot bennett at embecosm dot com>
- To: Pedro Alves <palves at redhat dot com>, gdb-patches at sourceware dot org
- Date: Thu, 07 Mar 2013 08:52:16 +0000
- Subject: Re: [PATCH PR gdb/15236] gdbserver write to linux memory with zero length corrupts stack
- References: <1362593035.2235.57.camel@laria> <513793BD.2090804@redhat.com>
- Reply-to: jeremy dot bennett at embecosm dot com
On Wed, 2013-03-06 at 19:06 +0000, Pedro Alves wrote:
> Hi Jeremy,
>
> Thanks for the diagnosis and the patch.
Pedro, thanks for the comments. I've revised the patch accordingly.
Since I don't have write permission, would you commit it for me. Here is
the corrected ChangeLog entry:
2013-03-07 Jeremy Bennett <jeremy.bennett@embecosm.com>
PR gdb/15236
* linux-low.c (linux_write_memory): Return early success if LEN is
zero.
Here is the corrected patch:
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index a8cf78c..d7202fd 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,9 @@
+2013-03-07 Jeremy Bennett <jeremy.bennett@embecosm.com>
+
+ PR gdb/15236
+ * linux-low.c (linux_write_memory): Return early success if LEN is
+ zero.
+
2013-03-05 Corinna Vinschen <vinschen@redhat.de>
* configure.srv: Add x86_64-*-cygwin* as target.
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index c52cd2e..8eb5dac 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -4481,7 +4481,7 @@ linux_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
/* Copy LEN bytes of data from debugger memory at MYADDR to inferior's
memory at MEMADDR. On failure (cannot write to the inferior)
- returns the value of errno. */
+ returns the value of errno. Succeeds immediately if LEN is zero. */
static int
linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
@@ -4500,6 +4500,12 @@ linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
int pid = lwpid_of (get_thread_lwp (current_inferior));
+ if (len == 0)
+ {
+ /* Zero length write always succeeds. */
+ return 0;
+ }
+
if (debug_threads)
{
/* Dump up to four bytes. */
Best wishes,
Jeremy
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