Hi, On Thu, Dec 22, 2016 at 2:12 AM, <mcchou@xxxxxxxxxxxx> wrote: > From: Miao-chen Chou <mcchou@xxxxxxxxxxxx> > > This patch removes "packed" attribute from the definition of struct rfcomm_rpn > to prevent the access to an unaligned struct member in mmc_rpn(). This patch > also introduces a temp variable in mcc_pn() to prevent unaligned access without > touching the definition of struct rfcomm_pn, since struct rfcomm_pn is used as > a PDU. > > error messages from LLVM build: > > monitor/rfcomm.c:238:36: error: taking address of packed member 'pm' of class > or structure 'rfcomm_rpn' may result in an unaligned pointer value > [-Werror,-Waddress-of-packed-member] > if (!l2cap_frame_get_le16(frame, &rpn.pm)) > monitor/rfcomm.c:287:36: error: taking address of packed member 'mtu' of class > or structure 'rfcomm_pn' may result in an unaligned pointer value > [-Werror,-Waddress-of-packed-member] > if (!l2cap_frame_get_le16(frame, &pn.mtu)) > > Currently there is no corresponding flag in GCC to generate the same error > messages. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51628. > --- > v5 adds more details about the error messages. > > monitor/rfcomm.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/monitor/rfcomm.c b/monitor/rfcomm.c > index fd7bbdc..afeb5e1 100644 > --- a/monitor/rfcomm.c > +++ b/monitor/rfcomm.c > @@ -106,7 +106,7 @@ struct rfcomm_rpn { > uint8_t xon; > uint8_t xoff; > uint16_t pm; > -} __attribute__ ((packed)); > +}; > > struct rfcomm_rls { > uint8_t dlci; > @@ -265,6 +265,7 @@ static inline bool mcc_pn(struct rfcomm_frame *rfcomm_frame, uint8_t indent) > { > struct l2cap_frame *frame = &rfcomm_frame->l2cap_frame; > struct rfcomm_pn pn; > + uint16_t mtu; > > /* rfcomm_pn struct is defined in rfcomm.h */ > > @@ -284,8 +285,10 @@ static inline bool mcc_pn(struct rfcomm_frame *rfcomm_frame, uint8_t indent) > if (!l2cap_frame_get_u8(frame, &pn.ack_timer)) > return false; > > - if (!l2cap_frame_get_le16(frame, &pn.mtu)) > + /* prevent unaligned memory access */ > + if (!l2cap_frame_get_le16(frame, &mtu)) > return false; > + pn.mtu = mtu; > > if (!l2cap_frame_get_u8(frame, &pn.max_retrans)) > return false; > -- > 2.8.0.rc3.226.g39d4020 Applied, thanks. -- Luiz Augusto von Dentz -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
