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Cygwin: wcsxfrm_l: Only byte swap if dest size is > 0

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commit c0d7d3e1a2fa96db15613cbd68a68c96966bc402 removed the usage of the
LCMAP_BYTEREV flag in the call to LCMapStringW to workaround a strange
bug in LCMapStringW.  This patch didn't take a userspace call of
wcsxfrm{_l} with NULL buffer and 0 size to evaluate the required buffer
size into account.  This introduced a crash trying to byte swap the
NULL buffer.  This patch fixes that problem.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2019-03-19 20:56:11 +01:00
parent 62c66a39bd
commit 10900b98d1
2 changed files with 15 additions and 9 deletions
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21
winsup/cygwin/nlsfuncs.cc
View File

@ -1204,15 +1204,18 @@ wcsxfrm_l (wchar_t *__restrict ws1, const wchar_t *__restrict ws2, size_t wsn,
if (ret)
{
ret /= sizeof (wchar_t);
/* Byte swap the array ourselves here. */
for (size_t idx = 0; idx < ret; ++idx)
ws1[idx] = __builtin_bswap16 (ws1[idx]);
/* LCMapStringW returns byte count including the terminating NUL char.
wcsxfrm is supposed to return length in wchar_t excluding the NUL.
Since the array is only single byte NUL-terminated yet, make sure
the result is wchar_t-NUL terminated. */
if (ret < wsn)
ws1[ret] = L'\0';
if (wsn)
{
/* Byte swap the array ourselves here. */
for (size_t idx = 0; idx < ret; ++idx)
ws1[idx] = __builtin_bswap16 (ws1[idx]);
/* LCMapStringW returns byte count including the terminating NUL char.
wcsxfrm is supposed to return length in wchar_t excluding the NUL.
Since the array is only single byte NUL-terminated yet, make sure
the result is wchar_t-NUL terminated. */
if (ret < wsn)
ws1[ret] = L'\0';
}
return ret;
}
if (GetLastError () != ERROR_INSUFFICIENT_BUFFER)

3
winsup/cygwin/release/3.0.5
View File

@ -11,3 +11,6 @@ Bug Fixes
- Fix /proc/version after uname change
Addresses: https://cygwin.com/ml/cygwin/2019-03/msg00467.html
- Fix a crash in wcsxfrm_l if destination size is 0.
Addresses: https://cygwin.com/ml/cygwin/2019-03/msg00492.html