diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2016-06-13 11:22:05 +0100 |
|---|---|---|
| committer | Riku Voipio <riku.voipio@linaro.org> | 2016-06-24 11:55:44 +0300 |
| commit | 55d72a7eb32858d50ba0777cfde2027d007010b2 (patch) | |
| tree | aee8282bced8d478e2315c800e1bff4c5e215bf9 | |
| parent | c7288767523f6510cf557707d3eb5e78e519b90d (diff) | |
linux-user: Avoid possible misalignment in host_to_target_siginfo()
host_to_target_siginfo() is implemented by a combination of
host_to_target_siginfo_noswap() followed by tswap_siginfo().
The first of these two functions assumes that the target_siginfo_t
it is writing to is correctly aligned, but the pointer passed
into host_to_target_siginfo() is directly from the guest and
might be misaligned. Use a local variable to avoid this problem.
(tswap_siginfo() does now correctly handle a misaligned destination.)
We have to add a memset() to host_to_target_siginfo_noswap()
to avoid some false positive "may be used uninitialized" warnings
from gcc about subfields of the _sifields union if it chooses to
inline both tswap_siginfo() and host_to_target_siginfo_noswap()
into host_to_target_siginfo().
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Peter Maydell <riku.voipio@linaro.org>
| -rw-r--r-- | linux-user/signal.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/linux-user/signal.c b/linux-user/signal.c index 1dadddf2dd..e2d55fff97 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -278,6 +278,14 @@ static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo, tinfo->si_errno = 0; tinfo->si_code = info->si_code; + /* This memset serves two purposes: + * (1) ensure we don't leak random junk to the guest later + * (2) placate false positives from gcc about fields + * being used uninitialized if it chooses to inline both this + * function and tswap_siginfo() into host_to_target_siginfo(). + */ + memset(tinfo->_sifields._pad, 0, sizeof(tinfo->_sifields._pad)); + /* This is awkward, because we have to use a combination of * the si_code and si_signo to figure out which of the union's * members are valid. (Within the host kernel it is always possible @@ -397,8 +405,9 @@ static void tswap_siginfo(target_siginfo_t *tinfo, void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info) { - host_to_target_siginfo_noswap(tinfo, info); - tswap_siginfo(tinfo, tinfo); + target_siginfo_t tgt_tmp; + host_to_target_siginfo_noswap(&tgt_tmp, info); + tswap_siginfo(tinfo, &tgt_tmp); } /* XXX: we support only POSIX RT signals are used. */ |