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dlfcn: Avoid one-element flexible array in Dl_serinfo [BZ #24166]

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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.
This commit is contained in:
Florian Weimer 2019-06-19 10:13:50 +02:00
parent 2c75b545de
commit fabf5e49dd
2 changed files with 18 additions and 0 deletions
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ChangeLog
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@ -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]

12
dlfcn/dlfcn.h
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@ -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 */