From 9946a9113cf5d84c9381342100343aa97f736ee0 Mon Sep 17 00:00:00 2001 From: Alexander Yarygin Date: Mon, 10 Aug 2015 13:57:03 +0300 Subject: [PATCH] s390x/ipl: Add type and length checks for IplParameterBlock values We can check for valid type and lengths of the IplParameterBlock fields when receiving the struct from the guest. Length of the IplParameterBlock can be less than 4K. To play safe we can read and write only required amount of data. Signed-off-by: Alexander Yarygin Reviewed-by: David Hildenband Acked-by: Christian Borntraeger Signed-off-by: Cornelia Huck --- hw/s390x/ipl.h | 21 +++++++++++++++++++++ target-s390x/misc_helper.c | 17 +++++++++++++++-- 2 files changed, 36 insertions(+), 2 deletions(-) diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h index 73b86e3f81..08f1d5c385 100644 --- a/hw/s390x/ipl.h +++ b/hw/s390x/ipl.h @@ -99,6 +99,27 @@ struct S390IPLState { }; typedef struct S390IPLState S390IPLState; +#define S390_IPL_TYPE_FCP 0x00 +#define S390_IPL_TYPE_CCW 0x02 + #define S390_IPLB_MIN_CCW_LEN 200 +#define S390_IPLB_MIN_FCP_LEN 384 + +static inline bool iplb_valid_len(IplParameterBlock *iplb) +{ + return be32_to_cpu(iplb->len) <= sizeof(IplParameterBlock); +} + +static inline bool iplb_valid_ccw(IplParameterBlock *iplb) +{ + return be32_to_cpu(iplb->len) >= S390_IPLB_MIN_CCW_LEN && + iplb->pbt == S390_IPL_TYPE_CCW; +} + +static inline bool iplb_valid_fcp(IplParameterBlock *iplb) +{ + return be32_to_cpu(iplb->len) >= S390_IPLB_MIN_FCP_LEN && + iplb->pbt == S390_IPL_TYPE_FCP; +} #endif diff --git a/target-s390x/misc_helper.c b/target-s390x/misc_helper.c index fab7f87a8f..462cfc85fc 100644 --- a/target-s390x/misc_helper.c +++ b/target-s390x/misc_helper.c @@ -233,9 +233,22 @@ void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3) return; } iplb = g_malloc0(sizeof(IplParameterBlock)); - cpu_physical_memory_read(addr, iplb, S390_IPLB_MIN_CCW_LEN); + cpu_physical_memory_read(addr, iplb, sizeof(iplb->len)); + if (!iplb_valid_len(iplb)) { + env->regs[r1 + 1] = DIAG_308_RC_INVALID; + goto out; + } + + cpu_physical_memory_read(addr, iplb, be32_to_cpu(iplb->len)); + + if (!iplb_valid_ccw(iplb) && !iplb_valid_fcp(iplb)) { + env->regs[r1 + 1] = DIAG_308_RC_INVALID; + goto out; + } + s390_ipl_update_diag308(iplb); env->regs[r1 + 1] = DIAG_308_RC_OK; +out: g_free(iplb); return; case 6: @@ -250,7 +263,7 @@ void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3) } iplb = s390_ipl_get_iplb(); if (iplb) { - cpu_physical_memory_write(addr, iplb, S390_IPLB_MIN_CCW_LEN); + cpu_physical_memory_write(addr, iplb, be32_to_cpu(iplb->len)); env->regs[r1 + 1] = DIAG_308_RC_OK; } else { env->regs[r1 + 1] = DIAG_308_RC_NO_CONF; -- GitLab