Re: [PATCH] kernel: tsacct: strncpy, always be sure of NUL terminated.
On 2013年04月08日 11:52, KOSAKI Motohiro wrote: > On Sun, Apr 7, 2013 at 11:27 PM, Chen Gang wrote: >> > >> > for NUL terminated string, always set '\0' at the end. >> > >> > Signed-off-by: Chen Gang >> > --- >> > kernel/tsacct.c |3 ++- >> > 1 files changed, 2 insertions(+), 1 deletions(-) >> > >> > diff --git a/kernel/tsacct.c b/kernel/tsacct.c >> > index a1dd9a1..01bcc4e 100644 >> > --- a/kernel/tsacct.c >> > +++ b/kernel/tsacct.c >> > @@ -78,7 +78,8 @@ void bacct_add_tsk(struct user_namespace *user_ns, >> > stats->ac_minflt = tsk->min_flt; >> > stats->ac_majflt = tsk->maj_flt; >> > >> > - strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm)); >> > + strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm) - 1); >> > + stats->ac_comm[sizeof(stats->ac_comm) - 1] = '\0'; > sizeof(tsk->comm) is 16 and sizeof(stats->ac_comm) is 32. then this statement > is strange. and set_task_comm ensure tsk->comm is nul-terminated. > > so your code never change the behavior, right? > right. thank you for your information: originally, I really did not check the sizeof details. > And, If buggy driver change tsk->comm not to use set_task_comm and tsk->comm > is not nul-terminated, strncpy() still touch unrelated memory and ac_comm may > expose kernel internal info. that's bad. > > really, that's bad ! thank you for your information: originally, I did not think of a buggy driver can change tsk->comm. :-) -- Chen Gang Asianux Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] kernel: tsacct: strncpy, always be sure of NUL terminated.
On Sun, Apr 7, 2013 at 11:27 PM, Chen Gang wrote: > > for NUL terminated string, always set '\0' at the end. > > Signed-off-by: Chen Gang > --- > kernel/tsacct.c |3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/kernel/tsacct.c b/kernel/tsacct.c > index a1dd9a1..01bcc4e 100644 > --- a/kernel/tsacct.c > +++ b/kernel/tsacct.c > @@ -78,7 +78,8 @@ void bacct_add_tsk(struct user_namespace *user_ns, > stats->ac_minflt = tsk->min_flt; > stats->ac_majflt = tsk->maj_flt; > > - strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm)); > + strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm) - 1); > + stats->ac_comm[sizeof(stats->ac_comm) - 1] = '\0'; sizeof(tsk->comm) is 16 and sizeof(stats->ac_comm) is 32. then this statement is strange. and set_task_comm ensure tsk->comm is nul-terminated. so your code never change the behavior, right? And, If buggy driver change tsk->comm not to use set_task_comm and tsk->comm is not nul-terminated, strncpy() still touch unrelated memory and ac_comm may expose kernel internal info. that's bad. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] kernel: tsacct: strncpy, always be sure of NUL terminated.
for NUL terminated string, always set '\0' at the end. Signed-off-by: Chen Gang --- kernel/tsacct.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/tsacct.c b/kernel/tsacct.c index a1dd9a1..01bcc4e 100644 --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -78,7 +78,8 @@ void bacct_add_tsk(struct user_namespace *user_ns, stats->ac_minflt = tsk->min_flt; stats->ac_majflt = tsk->maj_flt; - strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm)); + strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm) - 1); + stats->ac_comm[sizeof(stats->ac_comm) - 1] = '\0'; } -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] kernel: tsacct: strncpy, always be sure of NUL terminated.
for NUL terminated string, always set '\0' at the end. Signed-off-by: Chen Gang gang.c...@asianux.com --- kernel/tsacct.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/tsacct.c b/kernel/tsacct.c index a1dd9a1..01bcc4e 100644 --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -78,7 +78,8 @@ void bacct_add_tsk(struct user_namespace *user_ns, stats-ac_minflt = tsk-min_flt; stats-ac_majflt = tsk-maj_flt; - strncpy(stats-ac_comm, tsk-comm, sizeof(stats-ac_comm)); + strncpy(stats-ac_comm, tsk-comm, sizeof(stats-ac_comm) - 1); + stats-ac_comm[sizeof(stats-ac_comm) - 1] = '\0'; } -- 1.7.7.6 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] kernel: tsacct: strncpy, always be sure of NUL terminated.
On Sun, Apr 7, 2013 at 11:27 PM, Chen Gang gang.c...@asianux.com wrote: for NUL terminated string, always set '\0' at the end. Signed-off-by: Chen Gang gang.c...@asianux.com --- kernel/tsacct.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/tsacct.c b/kernel/tsacct.c index a1dd9a1..01bcc4e 100644 --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -78,7 +78,8 @@ void bacct_add_tsk(struct user_namespace *user_ns, stats-ac_minflt = tsk-min_flt; stats-ac_majflt = tsk-maj_flt; - strncpy(stats-ac_comm, tsk-comm, sizeof(stats-ac_comm)); + strncpy(stats-ac_comm, tsk-comm, sizeof(stats-ac_comm) - 1); + stats-ac_comm[sizeof(stats-ac_comm) - 1] = '\0'; sizeof(tsk-comm) is 16 and sizeof(stats-ac_comm) is 32. then this statement is strange. and set_task_comm ensure tsk-comm is nul-terminated. so your code never change the behavior, right? And, If buggy driver change tsk-comm not to use set_task_comm and tsk-comm is not nul-terminated, strncpy() still touch unrelated memory and ac_comm may expose kernel internal info. that's bad. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] kernel: tsacct: strncpy, always be sure of NUL terminated.
On 2013年04月08日 11:52, KOSAKI Motohiro wrote: On Sun, Apr 7, 2013 at 11:27 PM, Chen Gang gang.c...@asianux.com wrote: for NUL terminated string, always set '\0' at the end. Signed-off-by: Chen Gang gang.c...@asianux.com --- kernel/tsacct.c |3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/tsacct.c b/kernel/tsacct.c index a1dd9a1..01bcc4e 100644 --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -78,7 +78,8 @@ void bacct_add_tsk(struct user_namespace *user_ns, stats-ac_minflt = tsk-min_flt; stats-ac_majflt = tsk-maj_flt; - strncpy(stats-ac_comm, tsk-comm, sizeof(stats-ac_comm)); + strncpy(stats-ac_comm, tsk-comm, sizeof(stats-ac_comm) - 1); + stats-ac_comm[sizeof(stats-ac_comm) - 1] = '\0'; sizeof(tsk-comm) is 16 and sizeof(stats-ac_comm) is 32. then this statement is strange. and set_task_comm ensure tsk-comm is nul-terminated. so your code never change the behavior, right? right. thank you for your information: originally, I really did not check the sizeof details. And, If buggy driver change tsk-comm not to use set_task_comm and tsk-comm is not nul-terminated, strncpy() still touch unrelated memory and ac_comm may expose kernel internal info. that's bad. really, that's bad ! thank you for your information: originally, I did not think of a buggy driver can change tsk-comm. :-) -- Chen Gang Asianux Corporation -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
