From: Anton Lavrentiev <lavr@ncbi.nlm.nih.gov>
To: cygwin-patches@cygwin.com
Subject: [PATCH] Cygwin: resolver: A few fixes for cygwin_query()
Date: Tue, 18 Jan 2022 16:34:34 -0500 [thread overview]
Message-ID: <20220118213434.35894-1-lavr@ncbi.nlm.nih.gov> (raw)
- Make sure the answer buffer is properly cleared so there is no trailing
garbage when the response does not fit entirely in;
- Make sure an internal decomp failure gets reported correctly (w/return code -1);
- Make sure that the buffer is not overrun when filling out the header.
---
winsup/cygwin/libc/minires-os-if.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/winsup/cygwin/libc/minires-os-if.c b/winsup/cygwin/libc/minires-os-if.c
index bb6786f6c..c4183db9c 100644
--- a/winsup/cygwin/libc/minires-os-if.c
+++ b/winsup/cygwin/libc/minires-os-if.c
@@ -193,6 +193,8 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
dnptrs[0] = AnsPtr;
dnptrs[1] = NULL;
+ memset(AnsPtr, 0, AnsLength);
+
if (Class != ns_c_in) {
errno = ENOSYS;
statp->res_h_errno = NETDB_INTERNAL;
@@ -214,7 +216,7 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
switch (res) {
case ERROR_INVALID_NAME:
errno = EINVAL;
- statp->res_h_errno = NETDB_INTERNAL;;
+ statp->res_h_errno = NETDB_INTERNAL;
break;
case ERROR_TIMEOUT:
statp->res_h_errno = TRY_AGAIN;
@@ -259,8 +261,9 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
/* No question. Adopt the first name as the name in the question */
if ((len = dn_comp(rr->pName, ptr, AnsLength - 4,
dnptrs, &dnptrs[DIM(dnptrs) - 1])) < 0) {
- ptr = NULL;
- break;
+ statp->res_h_errno = NETDB_INTERNAL; /* dn_comp sets errno */
+ len = -1;
+ goto done;
}
ptr += len;
PUTSHORT(Type, ptr);
@@ -289,11 +292,13 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
len = ptr - AnsPtr;
done:
- ptr = AnsPtr;
- PUTSHORT(0, ptr); /* Id */
- PUTSHORT((QR << 8) + RA + RD, ptr);
- for (section = 0; section < DIM(counts); section++) {
- PUTSHORT(counts[section], ptr);
+ if (HFIXEDSZ <= AnsLength) {
+ ptr = AnsPtr;
+ PUTSHORT(0, ptr); /* Id */
+ PUTSHORT((QR << 8) + RA + RD, ptr);
+ for (section = 0; section < DIM(counts); section++) {
+ PUTSHORT(counts[section], ptr);
+ }
}
return len;
}
--
2.33.0
reply other threads:[~2022-01-18 21:34 UTC|newest]
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