| Message ID | 20200817152346.32092-1-Filip.Bozuta@syrmia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] linux-user: Fix 'semop()' and 'semtimedop()' implementation | expand |
Le 17/08/2020 à 17:23, Filip Bozuta a écrit : > The implementations of syscalls 'semop()' and 'semtimedop()' in > file 'syscall.c' use function 'target_to_host_sembuf()' to convert > values of 'struct sembuf' from host to target. However, before this > conversion it should be check whether the number of semaphore operations > 'nsops' is not bigger than maximum allowed semaphor operations per > syscall: 'SEMOPM'. In these cases, errno 'E2BIG' ("Arg list too long") > should be set. But the implementation will set errno 'EFAULT' ("Bad address") > in this case since the conversion from target to host in this case fails. > > This was confirmed with the LTP test for 'semop()' ('ipc/semop/semop02') in > test case where 'nsops' is greater than SEMOPM with unaproppriate errno EFAULT: > > semop02.c:130: FAIL: semop failed unexpectedly; expected: E2BIG: EFAULT (14) > > This patch changes this by adding a check whether 'nsops' is bigger than > 'SEMOPM' before the conversion function 'target_to_host_sembuf()' is called. > After the changes from this patch, the test works fine along with the other > LTP testcases for 'semop()'): > > semop02.c:126: PASS: semop failed as expected: E2BIG (7) > > Implementation notes: > > A target value ('TARGET_SEMOPM') was added for 'SEMOPM' as to be sure > in case the value is not available for some targets. > > Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com> > --- > linux-user/syscall.c | 12 ++++++++++-- > linux-user/syscall_defs.h | 2 ++ > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index 1211e759c2..70b172740c 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -3904,7 +3904,7 @@ static inline abi_long do_semtimedop(int semid, > unsigned nsops, > abi_long timeout) > { > - struct sembuf sops[nsops]; > + struct sembuf *sops = NULL; No need to set it to NULL. > struct timespec ts, *pts = NULL; > abi_long ret; > > @@ -3915,8 +3915,15 @@ static inline abi_long do_semtimedop(int semid, > } > } > > - if (target_to_host_sembuf(sops, ptr, nsops)) > + if (nsops > TARGET_SEMOPM) { > + return -TARGET_E2BIG; > + } > + > + sops = g_new(struct sembuf, nsops); > + > + if (target_to_host_sembuf(sops, ptr, nsops)) { Add: g_free(sops); > return -TARGET_EFAULT; > + } > > ret = -TARGET_ENOSYS; > #ifdef __NR_semtimedop Thanks, Laurent
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 1211e759c2..70b172740c 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -3904,7 +3904,7 @@ static inline abi_long do_semtimedop(int semid, unsigned nsops, abi_long timeout) { - struct sembuf sops[nsops]; + struct sembuf *sops = NULL; struct timespec ts, *pts = NULL; abi_long ret; @@ -3915,8 +3915,15 @@ static inline abi_long do_semtimedop(int semid, } } - if (target_to_host_sembuf(sops, ptr, nsops)) + if (nsops > TARGET_SEMOPM) { + return -TARGET_E2BIG; + } + + sops = g_new(struct sembuf, nsops); + + if (target_to_host_sembuf(sops, ptr, nsops)) { return -TARGET_EFAULT; + } ret = -TARGET_ENOSYS; #ifdef __NR_semtimedop @@ -3928,6 +3935,7 @@ static inline abi_long do_semtimedop(int semid, SEMTIMEDOP_IPC_ARGS(nsops, sops, (long)pts))); } #endif + g_free(sops); return ret; } #endif diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h index 3c261cff0e..f7f77346be 100644 --- a/linux-user/syscall_defs.h +++ b/linux-user/syscall_defs.h @@ -46,6 +46,8 @@ #define IPCOP_shmget 23 #define IPCOP_shmctl 24 +#define TARGET_SEMOPM 500 + /* * The following is for compatibility across the various Linux * platforms. The i386 ioctl numbering scheme doesn't really enforce
The implementations of syscalls 'semop()' and 'semtimedop()' in file 'syscall.c' use function 'target_to_host_sembuf()' to convert values of 'struct sembuf' from host to target. However, before this conversion it should be check whether the number of semaphore operations 'nsops' is not bigger than maximum allowed semaphor operations per syscall: 'SEMOPM'. In these cases, errno 'E2BIG' ("Arg list too long") should be set. But the implementation will set errno 'EFAULT' ("Bad address") in this case since the conversion from target to host in this case fails. This was confirmed with the LTP test for 'semop()' ('ipc/semop/semop02') in test case where 'nsops' is greater than SEMOPM with unaproppriate errno EFAULT: semop02.c:130: FAIL: semop failed unexpectedly; expected: E2BIG: EFAULT (14) This patch changes this by adding a check whether 'nsops' is bigger than 'SEMOPM' before the conversion function 'target_to_host_sembuf()' is called. After the changes from this patch, the test works fine along with the other LTP testcases for 'semop()'): semop02.c:126: PASS: semop failed as expected: E2BIG (7) Implementation notes: A target value ('TARGET_SEMOPM') was added for 'SEMOPM' as to be sure in case the value is not available for some targets. Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com> --- linux-user/syscall.c | 12 ++++++++++-- linux-user/syscall_defs.h | 2 ++ 2 files changed, 12 insertions(+), 2 deletions(-)