git: dc3509f1aafc - main - zlib: Fix a bug when getting a gzip header extra field with inflate().

The branch main has been updated by emaste:

URL: https://cgit.FreeBSD.org/src/commit/?id=dc3509f1aafcd966f3dd9226115cf94b691ff3c7

commit dc3509f1aafcd966f3dd9226115cf94b691ff3c7
Author:     Mark Adler <fork@madler.net>
AuthorDate: 2022-07-30 22:51:11 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2022-08-05 02:30:20 +0000

    zlib: Fix a bug when getting a gzip header extra field with inflate().
    
    If the extra field was larger than the space the user provided with
    inflateGetHeader(), and if multiple calls of inflate() delivered
    the extra header data, then there could be a buffer overflow of the
    provided space. This commit assures that provided space is not
    exceeded.
    
    (cherry picked from zlib commit eff308af425b67093bab25f80f1ae950166bece1)
---
 sys/contrib/zlib/inflate.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sys/contrib/zlib/inflate.c b/sys/contrib/zlib/inflate.c
index 499626d87a1c..345366eed406 100644
--- a/sys/contrib/zlib/inflate.c
+++ b/sys/contrib/zlib/inflate.c
@@ -763,9 +763,10 @@ int flush;
                 copy = state->length;
                 if (copy > have) copy = have;
                 if (copy) {
+                    len = state->head->extra_len - state->length;
                     if (state->head != Z_NULL &&
-                        state->head->extra != Z_NULL) {
-                        len = state->head->extra_len - state->length;
+                        state->head->extra != Z_NULL &&
+                        len < state->head->extra_max) {
                         zmemcpy(state->head->extra + len, next,
                                 len + copy > state->head->extra_max ?
                                 state->head->extra_max - len : copy);