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authorFlorian Weimer <fweimer@redhat.com>2019-06-19 10:13:50 +0200
committerFlorian Weimer <fweimer@redhat.com>2019-06-19 10:13:50 +0200
commitfabf5e49ddd61312027de8e92cc1b8528c2a929d (patch)
tree9f37dc7b29751182fd7ba7d091e1909cad314ef1
parent2c75b545de6fe3c44138799c68217a94bc669a88 (diff)
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dlfcn: Avoid one-element flexible array in Dl_serinfo [BZ #24166]
The dls_serpath path field, as an array of length 1, introduces unexpected array subscript checks with some compilers. GCC versions before 3.0 treat the nested anonymous union as a declaration of an unnamed type, and not as a member declaration, so this construct cannot be used for these compilers.
-rw-r--r--ChangeLog6
-rw-r--r--dlfcn/dlfcn.h12
2 files changed, 18 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index ac06595fb41..f32b734166d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-06-19 Florian Weimer <fweimer@redhat.com>
+
+ [BZ #24166]
+ * dlfcn/dlfcn.h (Dl_serinfo): Do not use array of length 1 for
+ dls_serpath field.
+
2019-06-18 Florian Weimer <fweimer@redhat.com>
[BZ #24323]
diff --git a/dlfcn/dlfcn.h b/dlfcn/dlfcn.h
index 896ad6fc9bf..c5503719994 100644
--- a/dlfcn/dlfcn.h
+++ b/dlfcn/dlfcn.h
@@ -180,7 +180,19 @@ typedef struct
{
size_t dls_size; /* Size in bytes of the whole buffer. */
unsigned int dls_cnt; /* Number of elements in `dls_serpath'. */
+# if __GNUC_PREREQ (3, 0)
+ /* The zero-length array avoids an unwanted array subscript check by
+ the compiler, while the surrounding anonymous union preserves the
+ historic size of the type. At the time of writing, GNU C does
+ not support structs with flexible array members in unions. */
+ __extension__ union
+ {
+ Dl_serpath dls_serpath[0]; /* Actually longer, dls_cnt elements. */
+ Dl_serpath __dls_serpath_pad[1];
+ };
+# else
Dl_serpath dls_serpath[1]; /* Actually longer, dls_cnt elements. */
+# endif
} Dl_serinfo;
#endif /* __USE_GNU */