diff options
Diffstat (limited to 'main/xen/xsa313-2.patch')
| -rw-r--r-- | main/xen/xsa313-2.patch | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/main/xen/xsa313-2.patch b/main/xen/xsa313-2.patch new file mode 100644 index 0000000000..d81b8232d2 --- /dev/null +++ b/main/xen/xsa313-2.patch @@ -0,0 +1,132 @@ +From: Jan Beulich <jbeulich@suse.com> +Subject: xenoprof: limit consumption of shared buffer data + +Since a shared buffer can be written to by the guest, we may only read +the head and tail pointers from there (all other fields should only ever +be written to). Furthermore, for any particular operation the two values +must be read exactly once, with both checks and consumption happening +with the thus read values. (The backtrace related xenoprof_buf_space() +use in xenoprof_log_event() is an exception: The values used there get +re-checked by every subsequent xenoprof_add_sample().) + +Since that code needed touching, also fix the double increment of the +lost samples count in case the backtrace related xenoprof_add_sample() +invocation in xenoprof_log_event() fails. + +Where code is being touched anyway, add const as appropriate, but take +the opportunity to entirely drop the now unused domain parameter of +xenoprof_buf_space(). + +This is part of XSA-313. + +Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com> +Signed-off-by: Jan Beulich <jbeulich@suse.com> +Reviewed-by: George Dunlap <george.dunlap@citrix.com> +Reviewed-by: Wei Liu <wl@xen.org> + +--- a/xen/common/xenoprof.c ++++ b/xen/common/xenoprof.c +@@ -479,25 +479,22 @@ static int add_passive_list(XEN_GUEST_HA + + + /* Get space in the buffer */ +-static int xenoprof_buf_space(struct domain *d, xenoprof_buf_t * buf, int size) ++static int xenoprof_buf_space(int head, int tail, int size) + { +- int head, tail; +- +- head = xenoprof_buf(d, buf, event_head); +- tail = xenoprof_buf(d, buf, event_tail); +- + return ((tail > head) ? 0 : size) + tail - head - 1; + } + + /* Check for space and add a sample. Return 1 if successful, 0 otherwise. */ +-static int xenoprof_add_sample(struct domain *d, xenoprof_buf_t *buf, ++static int xenoprof_add_sample(const struct domain *d, ++ const struct xenoprof_vcpu *v, + uint64_t eip, int mode, int event) + { ++ xenoprof_buf_t *buf = v->buffer; + int head, tail, size; + + head = xenoprof_buf(d, buf, event_head); + tail = xenoprof_buf(d, buf, event_tail); +- size = xenoprof_buf(d, buf, event_size); ++ size = v->event_size; + + /* make sure indexes in shared buffer are sane */ + if ( (head < 0) || (head >= size) || (tail < 0) || (tail >= size) ) +@@ -506,7 +503,7 @@ static int xenoprof_add_sample(struct do + return 0; + } + +- if ( xenoprof_buf_space(d, buf, size) > 0 ) ++ if ( xenoprof_buf_space(head, tail, size) > 0 ) + { + xenoprof_buf(d, buf, event_log[head].eip) = eip; + xenoprof_buf(d, buf, event_log[head].mode) = mode; +@@ -530,7 +527,6 @@ static int xenoprof_add_sample(struct do + int xenoprof_add_trace(struct vcpu *vcpu, uint64_t pc, int mode) + { + struct domain *d = vcpu->domain; +- xenoprof_buf_t *buf = d->xenoprof->vcpu[vcpu->vcpu_id].buffer; + + /* Do not accidentally write an escape code due to a broken frame. */ + if ( pc == XENOPROF_ESCAPE_CODE ) +@@ -539,7 +535,8 @@ int xenoprof_add_trace(struct vcpu *vcpu + return 0; + } + +- return xenoprof_add_sample(d, buf, pc, mode, 0); ++ return xenoprof_add_sample(d, &d->xenoprof->vcpu[vcpu->vcpu_id], ++ pc, mode, 0); + } + + void xenoprof_log_event(struct vcpu *vcpu, const struct cpu_user_regs *regs, +@@ -570,17 +567,22 @@ void xenoprof_log_event(struct vcpu *vcp + /* Provide backtrace if requested. */ + if ( backtrace_depth > 0 ) + { +- if ( (xenoprof_buf_space(d, buf, v->event_size) < 2) || +- !xenoprof_add_sample(d, buf, XENOPROF_ESCAPE_CODE, mode, +- XENOPROF_TRACE_BEGIN) ) ++ if ( xenoprof_buf_space(xenoprof_buf(d, buf, event_head), ++ xenoprof_buf(d, buf, event_tail), ++ v->event_size) < 2 ) + { + xenoprof_buf(d, buf, lost_samples)++; + lost_samples++; + return; + } ++ ++ /* xenoprof_add_sample() will increment lost_samples on failure */ ++ if ( !xenoprof_add_sample(d, v, XENOPROF_ESCAPE_CODE, mode, ++ XENOPROF_TRACE_BEGIN) ) ++ return; + } + +- if ( xenoprof_add_sample(d, buf, pc, mode, event) ) ++ if ( xenoprof_add_sample(d, v, pc, mode, event) ) + { + if ( is_active(vcpu->domain) ) + active_samples++; +--- a/xen/include/xen/xenoprof.h ++++ b/xen/include/xen/xenoprof.h +@@ -61,12 +61,12 @@ struct xenoprof { + + #ifndef CONFIG_COMPAT + #define XENOPROF_COMPAT(x) 0 +-#define xenoprof_buf(d, b, field) ((b)->field) ++#define xenoprof_buf(d, b, field) ACCESS_ONCE((b)->field) + #else + #define XENOPROF_COMPAT(x) ((x)->is_compat) +-#define xenoprof_buf(d, b, field) (*(!(d)->xenoprof->is_compat ? \ +- &(b)->native.field : \ +- &(b)->compat.field)) ++#define xenoprof_buf(d, b, field) ACCESS_ONCE(*(!(d)->xenoprof->is_compat \ ++ ? &(b)->native.field \ ++ : &(b)->compat.field)) + #endif + + struct domain; |