Valery Ushakov writes:
> On Mon, Aug 07, 2023 at 23:58:50 +0200, Tobias Nygren wrote:
>
> > Is this sort of fix acceptable for the above cases?
> [...]
> > + ptrdiff_t offset = pos - buf;
> [...]
> > - pos = new_buf + (pos - buf);
> > + pos = new_buf + offset;
>
> I think so. But e.g. in this particular case I don't see why pos
> pointer is needed at all. If pos is made into a size_t pos; index
> into the buf instead of a separate pointer, one avoids the whole thing
> and "end" can be g/c'ed too, b/c you can just compare the index to the
> "buf_size". But the above kind of fix has the advantage of being more
> or less mechanical.
yup, i agree. if we can fix it better, please do, but i'm all for
making it "less bad" if not properly fixed like the above.
i've used this idiom in a couple of places, but didn't quite get it
working in several others.
these are the problematic files i've see:
lib/libc/net/gethnamaddr.c
lib/libedit/chartype.c
lib/libkvm/kvm_proc.c
usr.bin/find/misc.c
usr.bin/mail/fio.c
external/bsd/pdisk/dist/io.c
usr.bin/rs/rs.c
usr.bin/sort/files.c
the first 3 i worked around, eg below, but i think i only tested
the gethnamaddr.c portion so far.
.mrg.
Index: lib/libc/net/gethnamaddr.c
===================================================================
RCS file: /cvsroot/src/lib/libc/net/gethnamaddr.c,v
retrieving revision 1.94
diff -p -u -r1.94 gethnamaddr.c
--- lib/libc/net/gethnamaddr.c 19 Apr 2022 20:32:15 -0000 1.94
+++ lib/libc/net/gethnamaddr.c 7 Aug 2023 23:41:44 -0000
@@ -110,10 +110,11 @@ __weak_alias(gethostent,_gethostent)
#define addalias(d, s, arr, siz) do { \
if (d >= &arr[siz]) { \
+ size_t _off = d - arr; \
char **xptr = realloc(arr, (siz + 10) * sizeof(*arr)); \
if (xptr == NULL) \
goto nospc; \
- d = xptr + (d - arr); \
+ d = xptr + _off; \
arr = xptr; \
siz += 10; \
} \
Index: lib/libedit/chartype.c
===================================================================
RCS file: /cvsroot/src/lib/libedit/chartype.c,v
retrieving revision 1.36
diff -p -u -r1.36 chartype.c
--- lib/libedit/chartype.c 30 Oct 2022 19:11:31 -0000 1.36
+++ lib/libedit/chartype.c 7 Aug 2023 23:41:44 -0000
@@ -235,17 +235,17 @@ ct_visual_string(const wchar_t *s, ct_bu
}
/* failed to encode, need more buffer space */
- used = dst - conv->wbuff;
+ size_t sused = (uintptr_t)dst - (uintptr_t)conv->wbuff;
if (ct_conv_wbuff_resize(conv, conv->wsize + CT_BUFSIZ) == -1)
return NULL;
- dst = conv->wbuff + used;
+ dst = conv->wbuff + sused;
}
if (dst >= (conv->wbuff + conv->wsize)) { /* sigh */
- used = dst - conv->wbuff;
+ size_t sused = (uintptr_t)dst - (uintptr_t)conv->wbuff;
if (ct_conv_wbuff_resize(conv, conv->wsize + CT_BUFSIZ) == -1)
return NULL;
- dst = conv->wbuff + used;
+ dst = conv->wbuff + sused;
}
*dst = L'\0';
Index: lib/libkvm/kvm_proc.c
===================================================================
RCS file: /cvsroot/src/lib/libkvm/kvm_proc.c,v
retrieving revision 1.98
diff -p -u -r1.98 kvm_proc.c
--- lib/libkvm/kvm_proc.c 19 Apr 2022 20:32:16 -0000 1.98
+++ lib/libkvm/kvm_proc.c 7 Aug 2023 23:41:44 -0000
@@ -980,7 +980,7 @@ kvm_argv(kvm_t *kd, const struct minipro
if (len + cc > kd->argspc_len) {
ptrdiff_t off;
char **pp;
- char *op = kd->argspc;
+ uintptr_t op = (uintptr_t)kd->argspc;
kd->argspc_len *= 2;
kd->argspc = _kvm_realloc(kd, kd->argspc,
@@ -991,7 +991,7 @@ kvm_argv(kvm_t *kd, const struct minipro
* Adjust argv pointers in case realloc moved
* the string space.
*/
- off = kd->argspc - op;
+ off = (uintptr_t)kd->argspc - op;
for (pp = kd->argv; pp < argv; pp++)
*pp += off;
ap += off;
