From 643a654540579b0dcc7a206a4a7475276a41aff0 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Sat, 11 Feb 2006 17:55:52 -0800 Subject: [PATCH] [PATCH] select: fix returned timeval With David Woodhouse select() presently has a habit of increasing the value of the user's `timeout' argument on return. We were writing back a timeout larger than the original. We _deliberately_ round up, since we know we must wait at _least_ as long as the caller asks us to. The patch adds a couple of helper functions for magnitude comparison of timespecs and of timevals, and uses them to prevent the various poll and select functions from returning a timeout which is larger than the one which was passed in. The patch also fixes a bug in compat_sys_pselect7(): it was adding the new timeout value to the old one and was returning that. It should just return the new timeout value. (We have various handy timespec/timeval-to-from-nsec conversion functions in time.h. But this code open-codes it all). Cc: "David S. Miller" Cc: Andi Kleen Cc: Ulrich Drepper Cc: Thomas Gleixner Cc: george anzinger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/compat.c | 37 +++++++++++++++++++++++++------------ fs/select.c | 32 +++++++++++++++++++++++--------- include/linux/compat.h | 20 ++++++++++++++++++++ include/linux/time.h | 25 ++++++++++++++++++++++++- 4 files changed, 92 insertions(+), 22 deletions(-) diff --git a/fs/compat.c b/fs/compat.c index 70c5af4cc270..a2ba78bdf7f7 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -1751,11 +1751,15 @@ asmlinkage long compat_sys_select(int n, compat_ulong_t __user *inp, ret = compat_core_sys_select(n, inp, outp, exp, &timeout); if (tvp) { + struct compat_timeval rtv; + if (current->personality & STICKY_TIMEOUTS) goto sticky; - tv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); - tv.tv_sec = timeout; - if (copy_to_user(tvp, &tv, sizeof(tv))) { + rtv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); + rtv.tv_sec = timeout; + if (compat_timeval_compare(&rtv, &tv) < 0) + rtv = tv; + if (copy_to_user(tvp, &rtv, sizeof(rtv))) { sticky: /* * If an application puts its timeval in read-only @@ -1822,13 +1826,17 @@ asmlinkage long compat_sys_pselect7(int n, compat_ulong_t __user *inp, } while (!ret && !timeout && tsp && (ts.tv_sec || ts.tv_nsec)); if (tsp && !(current->personality & STICKY_TIMEOUTS)) { - ts.tv_sec += timeout / HZ; - ts.tv_nsec += (timeout % HZ) * (1000000000/HZ); - if (ts.tv_nsec >= 1000000000) { - ts.tv_sec++; - ts.tv_nsec -= 1000000000; + struct compat_timespec rts; + + rts.tv_sec = timeout / HZ; + rts.tv_nsec = (timeout % HZ) * (NSEC_PER_SEC/HZ); + if (rts.tv_nsec >= NSEC_PER_SEC) { + rts.tv_sec++; + rts.tv_nsec -= NSEC_PER_SEC; } - (void)copy_to_user(tsp, &ts, sizeof(ts)); + if (compat_timespec_compare(&rts, &ts) < 0) + rts = ts; + copy_to_user(tsp, &rts, sizeof(rts)); } if (ret == -ERESTARTNOHAND) { @@ -1918,12 +1926,17 @@ asmlinkage long compat_sys_ppoll(struct pollfd __user *ufds, sigprocmask(SIG_SETMASK, &sigsaved, NULL); if (tsp && timeout >= 0) { + struct compat_timespec rts; + if (current->personality & STICKY_TIMEOUTS) goto sticky; /* Yes, we know it's actually an s64, but it's also positive. */ - ts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * 1000; - ts.tv_sec = timeout; - if (copy_to_user(tsp, &ts, sizeof(ts))) { + rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * + 1000; + rts.tv_sec = timeout; + if (compat_timespec_compare(&rts, &ts) < 0) + rts = ts; + if (copy_to_user(tsp, &rts, sizeof(rts))) { sticky: /* * If an application puts its timeval in read-only diff --git a/fs/select.c b/fs/select.c index bc60a3e14ef3..6ce68a9c8976 100644 --- a/fs/select.c +++ b/fs/select.c @@ -398,11 +398,15 @@ asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp, ret = core_sys_select(n, inp, outp, exp, &timeout); if (tvp) { + struct timeval rtv; + if (current->personality & STICKY_TIMEOUTS) goto sticky; - tv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); - tv.tv_sec = timeout; - if (copy_to_user(tvp, &tv, sizeof(tv))) { + rtv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); + rtv.tv_sec = timeout; + if (timeval_compare(&rtv, &tv) < 0) + rtv = tv; + if (copy_to_user(tvp, &rtv, sizeof(rtv))) { sticky: /* * If an application puts its timeval in read-only @@ -460,11 +464,16 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp, ret = core_sys_select(n, inp, outp, exp, &timeout); if (tsp) { + struct timespec rts; + if (current->personality & STICKY_TIMEOUTS) goto sticky; - ts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * 1000; - ts.tv_sec = timeout; - if (copy_to_user(tsp, &ts, sizeof(ts))) { + rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * + 1000; + rts.tv_sec = timeout; + if (timespec_compare(&rts, &ts) < 0) + rts = ts; + if (copy_to_user(tsp, &rts, sizeof(rts))) { sticky: /* * If an application puts its timeval in read-only @@ -758,12 +767,17 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds, sigprocmask(SIG_SETMASK, &sigsaved, NULL); if (tsp && timeout >= 0) { + struct timespec rts; + if (current->personality & STICKY_TIMEOUTS) goto sticky; /* Yes, we know it's actually an s64, but it's also positive. */ - ts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * 1000; - ts.tv_sec = timeout; - if (copy_to_user(tsp, &ts, sizeof(ts))) { + rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * + 1000; + rts.tv_sec = timeout; + if (timespec_compare(&rts, &ts) < 0) + rts = ts; + if (copy_to_user(tsp, &rts, sizeof(rts))) { sticky: /* * If an application puts its timeval in read-only diff --git a/include/linux/compat.h b/include/linux/compat.h index f9ca534787e2..c9ab2a26348c 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -161,5 +161,25 @@ int copy_siginfo_to_user32(struct compat_siginfo __user *to, siginfo_t *from); int get_compat_sigevent(struct sigevent *event, const struct compat_sigevent __user *u_event); +static inline int compat_timeval_compare(struct compat_timeval *lhs, + struct compat_timeval *rhs) +{ + if (lhs->tv_sec < rhs->tv_sec) + return -1; + if (lhs->tv_sec > rhs->tv_sec) + return 1; + return lhs->tv_usec - rhs->tv_usec; +} + +static inline int compat_timespec_compare(struct compat_timespec *lhs, + struct compat_timespec *rhs) +{ + if (lhs->tv_sec < rhs->tv_sec) + return -1; + if (lhs->tv_sec > rhs->tv_sec) + return 1; + return lhs->tv_nsec - rhs->tv_nsec; +} + #endif /* CONFIG_COMPAT */ #endif /* _LINUX_COMPAT_H */ diff --git a/include/linux/time.h b/include/linux/time.h index 7b4dc36532bb..d9cdba54b789 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -33,11 +33,34 @@ struct timezone { #define NSEC_PER_SEC 1000000000L #define NSEC_PER_USEC 1000L -static __inline__ int timespec_equal(struct timespec *a, struct timespec *b) +static inline int timespec_equal(struct timespec *a, struct timespec *b) { return (a->tv_sec == b->tv_sec) && (a->tv_nsec == b->tv_nsec); } +/* + * lhs < rhs: return <0 + * lhs == rhs: return 0 + * lhs > rhs: return >0 + */ +static inline int timespec_compare(struct timespec *lhs, struct timespec *rhs) +{ + if (lhs->tv_sec < rhs->tv_sec) + return -1; + if (lhs->tv_sec > rhs->tv_sec) + return 1; + return lhs->tv_nsec - rhs->tv_nsec; +} + +static inline int timeval_compare(struct timeval *lhs, struct timeval *rhs) +{ + if (lhs->tv_sec < rhs->tv_sec) + return -1; + if (lhs->tv_sec > rhs->tv_sec) + return 1; + return lhs->tv_usec - rhs->tv_usec; +} + extern unsigned long mktime(const unsigned int year, const unsigned int mon, const unsigned int day, const unsigned int hour, const unsigned int min, const unsigned int sec); -- 2.30.2