| Message ID | 20171114013009.26716-1-lav@etersoft.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 2017-11-14 at 04:30 +0300, Vitaly Lipatov wrote: > for fcntl64 with F_GETLK64 we need use checking against COMPAT_LOFF_T_MAX. > > Fixes: 94073ad77fff2 "fs/locks: don't mess with the address limit in compat_fcntl64" > > Signed-off-by: Vitaly Lipatov <lav@etersoft.ru> > --- > fs/fcntl.c | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/fs/fcntl.c b/fs/fcntl.c > index 30f47d0..fa17f67 100644 > --- a/fs/fcntl.c > +++ b/fs/fcntl.c > @@ -604,6 +604,25 @@ static int fixup_compat_flock(struct flock *flock) > return 0; > } > > +/* > + * GETLK64 was successful and we need to return the data, but it needs to fit in > + * the compat structure. > + * l_start shouldn't be too big, unless the original start + end is greater than > + * COMPAT_LOFF_T_MAX, in which case the app was asking for trouble, so we return > + * -EOVERFLOW in that case. l_len could be too big, in which case we just > + * truncate it, and only allow the app to see that part of the conflicting lock > + * that might make sense to it anyway > + */ > + > +static int fixup_compat_l_flock(struct flock *flock) > +{ > + if (flock->l_start > COMPAT_LOFF_T_MAX) > + return -EOVERFLOW; > + if (flock->l_len > COMPAT_LOFF_T_MAX) > + flock->l_len = COMPAT_LOFF_T_MAX; > + return 0; > +} > + (cc'ing Christoph since he wrote the original patch) This patch looks correct to me, but could we rename it to fixup_compat_flock64 to match the other functions here? Also, I think this should probably go to stable -- any objections? > COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, > compat_ulong_t, arg) > { > @@ -644,7 +663,7 @@ COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, > err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); > if (err) > break; > - err = fixup_compat_flock(&flock); > + err = fixup_compat_l_flock(&flock); > if (err) > return err; > err = put_compat_flock64(&flock, compat_ptr(arg));
Jeff Layton писал 14.11.17 14:29: > (cc'ing Christoph since he wrote the original patch) > > This patch looks correct to me, but could we rename it to > fixup_compat_flock64 to match the other functions here? Sure, feel free to make any renames and so on.
diff --git a/fs/fcntl.c b/fs/fcntl.c index 30f47d0..fa17f67 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -604,6 +604,25 @@ static int fixup_compat_flock(struct flock *flock) return 0; } +/* + * GETLK64 was successful and we need to return the data, but it needs to fit in + * the compat structure. + * l_start shouldn't be too big, unless the original start + end is greater than + * COMPAT_LOFF_T_MAX, in which case the app was asking for trouble, so we return + * -EOVERFLOW in that case. l_len could be too big, in which case we just + * truncate it, and only allow the app to see that part of the conflicting lock + * that might make sense to it anyway + */ + +static int fixup_compat_l_flock(struct flock *flock) +{ + if (flock->l_start > COMPAT_LOFF_T_MAX) + return -EOVERFLOW; + if (flock->l_len > COMPAT_LOFF_T_MAX) + flock->l_len = COMPAT_LOFF_T_MAX; + return 0; +} + COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, compat_ulong_t, arg) { @@ -644,7 +663,7 @@ COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); if (err) break; - err = fixup_compat_flock(&flock); + err = fixup_compat_l_flock(&flock); if (err) return err; err = put_compat_flock64(&flock, compat_ptr(arg));
for fcntl64 with F_GETLK64 we need use checking against COMPAT_LOFF_T_MAX. Fixes: 94073ad77fff2 "fs/locks: don't mess with the address limit in compat_fcntl64" Signed-off-by: Vitaly Lipatov <lav@etersoft.ru> --- fs/fcntl.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-)