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[PATCH] Fix buffer overrun in fetch_register_using_p
- From: Richard Henderson <richard dot henderson at linaro dot org>
- To: gdb-patches at sourceware dot org
- Date: Wed, 10 Oct 2018 08:45:53 -0700
- Subject: [PATCH] Fix buffer overrun in fetch_register_using_p
If the packet returned from the gdbserver is too long,
the stack would be clobbered and gdb would crash.
gdb/
* remote.c (remote_target::fetch_register_using_p): Error if
more data is received than expected in the packet.
---
I am adding SVE support to QEMU's gdbserver stub, and managed to
tickle this bug in the process.
r~
---
gdb/remote.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/gdb/remote.c b/gdb/remote.c
index 724f41cf71..d68faf1046 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -7958,7 +7958,8 @@ remote_target::fetch_register_using_p (struct regcache *regcache,
struct gdbarch *gdbarch = regcache->arch ();
struct remote_state *rs = get_remote_state ();
char *buf, *p;
- gdb_byte *regp = (gdb_byte *) alloca (register_size (gdbarch, reg->regnum));
+ int size = register_size (gdbarch, reg->regnum);
+ gdb_byte *regp = (gdb_byte *) alloca (size);
int i;
if (packet_support (PACKET_p) == PACKET_DISABLE)
@@ -8003,6 +8004,8 @@ remote_target::fetch_register_using_p (struct regcache *regcache,
{
if (p[1] == 0)
error (_("fetch_register_using_p: early buf termination"));
+ if (i == size)
+ error (_("fetch_register_using_p: late buf termination"));
regp[i++] = fromhex (p[0]) * 16 + fromhex (p[1]);
p += 2;
--
2.17.1