| Message ID | 20180613061657.13632-1-ppandit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jun 13, 2018 at 11:46:57AM +0530, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > While reading file content via 'guest-file-read' command, > 'qmp_guest_file_read' routine allocates buffer of count+1 > bytes. It could overflow for large values of 'count'. > Add check to avoid it. No objection to this patch, but I would point out that even trying to read 'UINT32_MAX - 1' bytes is going to end in disaster. We'll allocate UINT32_MAX bytes of RAM to read the data. Then we'll allocate (UINT32_MAX / 3 + 1) * 4 + 1) bytes of RAM in g_base64_encode.... which incidentally is not checking for integer overflow either when calling g_malloc. Then our JSON formatting code will allocate at least that much RAM again, probably also not checking for overflow. I wouldn't be surprised if we allocate that much RAM yet again in some other part of the stack too. > > Reported-by: Fakhri Zulkifli <mohdfakhrizulkifli@gmail.com> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> > --- > qga/commands-posix.c | 2 +- > qga/commands-win32.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/qga/commands-posix.c b/qga/commands-posix.c > index eae817191b..068c0f0bd9 100644 > --- a/qga/commands-posix.c > +++ b/qga/commands-posix.c > @@ -458,7 +458,7 @@ struct GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count, > > if (!has_count) { > count = QGA_READ_COUNT_DEFAULT; > - } else if (count < 0) { > + } else if (count < 0 || count >= UINT32_MAX) { > error_setg(errp, "value '%" PRId64 "' is invalid for argument count", > count); > return NULL; > diff --git a/qga/commands-win32.c b/qga/commands-win32.c > index 70ee5379f6..73f31fa8c2 100644 > --- a/qga/commands-win32.c > +++ b/qga/commands-win32.c > @@ -318,7 +318,7 @@ GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count, > } > if (!has_count) { > count = QGA_READ_COUNT_DEFAULT; > - } else if (count < 0) { > + } else if (count < 0 || count >= UINT32_MAX) { > error_setg(errp, "value '%" PRId64 > "' is invalid for argument count", count); > return NULL; > -- > 2.17.1 > > Regards, Daniel
diff --git a/qga/commands-posix.c b/qga/commands-posix.c index eae817191b..068c0f0bd9 100644 --- a/qga/commands-posix.c +++ b/qga/commands-posix.c @@ -458,7 +458,7 @@ struct GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count, if (!has_count) { count = QGA_READ_COUNT_DEFAULT; - } else if (count < 0) { + } else if (count < 0 || count >= UINT32_MAX) { error_setg(errp, "value '%" PRId64 "' is invalid for argument count", count); return NULL; diff --git a/qga/commands-win32.c b/qga/commands-win32.c index 70ee5379f6..73f31fa8c2 100644 --- a/qga/commands-win32.c +++ b/qga/commands-win32.c @@ -318,7 +318,7 @@ GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count, } if (!has_count) { count = QGA_READ_COUNT_DEFAULT; - } else if (count < 0) { + } else if (count < 0 || count >= UINT32_MAX) { error_setg(errp, "value '%" PRId64 "' is invalid for argument count", count); return NULL;