From 807e2b6fce022707418bc8f61c069d91c613b3d2 Mon Sep 17 00:00:00 2001 From: Basil Salman Date: Wed, 11 Mar 2020 19:04:17 +0200 Subject: [PATCH] qga-win: prevent crash when executing guest-file-read with large count guest-file-read command is currently implemented to read from a file handle count number of bytes. when executed with a very large count number qemu-ga crashes. after some digging turns out that qemu-ga crashes after trying to allocate a buffer large enough to save the data read in it, the buffer was allocated using g_malloc0 which is not fail safe, and results a crash in case of failure. g_malloc0 was replaced with g_try_malloc0() which returns NULL on failure, A check was added for that case in order to prevent qemu-ga from crashing and to send a response to the qemu-ga client accordingly. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1594054 Signed-off-by: Basil Salman Reported-by: Fakhri Zulkifli Cc: qemu-stable@nongnu.org Signed-off-by: Michael Roth --- qga/commands-win32.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/qga/commands-win32.c b/qga/commands-win32.c index 9c744d6405..b49920e201 100644 --- a/qga/commands-win32.c +++ b/qga/commands-win32.c @@ -343,7 +343,13 @@ GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count, } fh = gfh->fh; - buf = g_malloc0(count+1); + buf = g_try_malloc0(count + 1); + if (!buf) { + error_setg(errp, + "failed to allocate sufficient memory " + "to complete the requested service"); + return NULL; + } is_ok = ReadFile(fh, buf, count, &read_count, NULL); if (!is_ok) { error_setg_win32(errp, GetLastError(), "failed to read file"); -- 2.11.0