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| author | Florian Weimer <fweimer@redhat.com> | 2018-06-01 10:41:03 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2018-06-01 10:41:03 +0200 |
| commit | 4e8a6346cd3da2d88bbad745a1769260d36f2783 (patch) | |
| tree | dcf9deeedd5263469fa425574c0ac671a8b43c2a /debug/vasprintf_chk.c | |
| parent | 50d004c91c942221b862a4a13a4b5f78cfb0d595 (diff) | |
| download | glibc-4e8a6346cd3da2d88bbad745a1769260d36f2783.tar.gz glibc-4e8a6346cd3da2d88bbad745a1769260d36f2783.tar.xz glibc-4e8a6346cd3da2d88bbad745a1769260d36f2783.zip | |
libio: Avoid _allocate_buffer, _free_buffer function pointers [BZ #23236]
These unmangled function pointers reside on the heap and could be targeted by exploit writers, effectively bypassing libio vtable validation. Instead, we ignore these pointers and always call malloc or free. In theory, this is a backwards-incompatible change, but using the global heap instead of the user-supplied callback functions should have little application impact. (The old libstdc++ implementation exposed this functionality via a public, undocumented constructor in its strstreambuf class.)
Diffstat (limited to 'debug/vasprintf_chk.c')
| -rw-r--r-- | debug/vasprintf_chk.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/debug/vasprintf_chk.c b/debug/vasprintf_chk.c index 46603d9538..48b4741651 100644 --- a/debug/vasprintf_chk.c +++ b/debug/vasprintf_chk.c @@ -55,8 +55,8 @@ __vasprintf_chk (char **result_ptr, int flags, const char *format, _IO_JUMPS (&sf._sbf) = &_IO_str_jumps; _IO_str_init_static_internal (&sf, string, init_string_size, string); sf._sbf._f._flags &= ~_IO_USER_BUF; - sf._s._allocate_buffer = (_IO_alloc_type) malloc; - sf._s._free_buffer = (_IO_free_type) free; + sf._s._allocate_buffer_unused = (_IO_alloc_type) malloc; + sf._s._free_buffer_unused = (_IO_free_type) free; /* For flags > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n can only come from read-only format strings. */ |