Message ID | 1452005723-1494-2-git-send-email-ppandit@redhat.com |
---|---|
State | New |
Headers | show |
Am 05.01.2016 um 15:55 schrieb P J P: > From: Prasad J Pandit <pjp@fedoraproject.org> > > When processing firmware configurations, an OOB r/w access occurs > if 's->cur_entry' is set to be invalid(FW_CFG_INVALID=0xffff). > Add a check to validate 's->cur_entry' to avoid such access. > > Reported-by: Donghai Zdh <donghai.zdh@alibaba-inc.com> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> > --- > hw/nvram/fw_cfg.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c > index 68eff77..ce026bc 100644 > --- a/hw/nvram/fw_cfg.c > +++ b/hw/nvram/fw_cfg.c > @@ -233,12 +233,15 @@ static void fw_cfg_reboot(FWCfgState *s) > static void fw_cfg_write(FWCfgState *s, uint8_t value) > { > int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL); > - FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; > + FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL : > + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; > > trace_fw_cfg_write(s, value); > > - if (s->cur_entry & FW_CFG_WRITE_CHANNEL && e->callback && > - s->cur_offset < e->len) { > + if (s->cur_entry != FW_CFG_INVALID > + && s->cur_entry & FW_CFG_WRITE_CHANNEL > + && e->callback > + && s->cur_offset < e->len) { I suggest to test e != NULL instead of s->cur_entry != FW_CFG_INVALID. Of course both variants are equivalent, but e != NULL might be easier to review and make work of static code analyzers easier, too. > e->data[s->cur_offset++] = value; > if (s->cur_offset == e->len) { > e->callback(e->callback_opaque, e->data); > @@ -267,7 +270,8 @@ static int fw_cfg_select(FWCfgState *s, uint16_t key) > static uint8_t fw_cfg_read(FWCfgState *s) > { > int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL); > - FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; > + FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL : > + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; > uint8_t ret; > > if (s->cur_entry == FW_CFG_INVALID || !e->data || s->cur_offset >= e->len) >
+-- On Tue, 5 Jan 2016, Stefan Weil wrote --+ | > - s->cur_offset < e->len) { | > + if (s->cur_entry != FW_CFG_INVALID | > + && s->cur_entry & FW_CFG_WRITE_CHANNEL | > + && e->callback | > + && s->cur_offset < e->len) { | | I suggest to test e != NULL instead of s->cur_entry != FW_CFG_INVALID. | | Of course both variants are equivalent, but e != NULL might be easier | to review and make work of static code analyzers easier, too. Yes, I've sent a revised patch with this change. Thank you. -- Prasad J Pandit / Red Hat Product Security Team 47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index 68eff77..ce026bc 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -233,12 +233,15 @@ static void fw_cfg_reboot(FWCfgState *s) static void fw_cfg_write(FWCfgState *s, uint8_t value) { int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL); - FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; + FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL : + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; trace_fw_cfg_write(s, value); - if (s->cur_entry & FW_CFG_WRITE_CHANNEL && e->callback && - s->cur_offset < e->len) { + if (s->cur_entry != FW_CFG_INVALID + && s->cur_entry & FW_CFG_WRITE_CHANNEL + && e->callback + && s->cur_offset < e->len) { e->data[s->cur_offset++] = value; if (s->cur_offset == e->len) { e->callback(e->callback_opaque, e->data); @@ -267,7 +270,8 @@ static int fw_cfg_select(FWCfgState *s, uint16_t key) static uint8_t fw_cfg_read(FWCfgState *s) { int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL); - FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; + FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL : + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK]; uint8_t ret; if (s->cur_entry == FW_CFG_INVALID || !e->data || s->cur_offset >= e->len)