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path: root/main/xen/xen-cmdline-Fix-buggy-strncmp-s-LITERAL-ss-s-constru.patch
blob: bbcc3a299f3a4798578051de25eddf6cdfd8b136 (plain) (blame)
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From e202feb7131e66ed9186ad8766c9582502c98998 Mon Sep 17 00:00:00 2001
From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Fri, 1 Feb 2019 11:34:35 +0100
Subject: [PATCH] xen/cmdline: Fix buggy strncmp(s, LITERAL, ss - s) construct

When the command line parsing was updated to use const strings and no longer
tokenise with NUL characters, string matches could no longer be made with
strcmp().

Unfortunately, the replacement was buggy.  strncmp(s, "opt", ss - s) matches
"o", "op" and "opt" on the command line, as ss - s may be shorter than the
passed literal.  Furthermore, parse_bool() is affected by this, so substrings
such as "d", "e" and "o" are considered valid, with the latter being ambiguous
between "on" and "off".

Introduce a new strcmp-like function for the task, which looks for exact
string matches, but declares success when the NUL of the literal matches a
comma, colon or semicolon in the command line fragment.

No change to the intended parsing functionality, but fixes cases where a
partial string on the command line will inadvertently trigger options.

A few areas were more than just a trivial change:

 * parse_irq_vector_map_param() gained some style corrections.
 * parse_vpmu_params() was rewritten to use the normal list-of-options form,
   rather than just fixing up parse_vpmu_param() and leaving the parsing being
   hard to follow.
 * Instead of making the trivial fix of adding an explicit length check in
   parse_bool(), use the length to select which token to we search for, which
   is more efficient than the previous linear search over all possible tokens.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien.grall@arm.com>
master commit: 2ddf7e3e341df3ccf21613ff7ffd4b7693abe9e9
master date: 2019-01-15 12:58:34 +0000
---
 xen/arch/x86/cpu/vpmu.c               | 49 ++++++-----------
 xen/arch/x86/irq.c                    | 12 ++--
 xen/arch/x86/psr.c                    |  4 +-
 xen/arch/x86/spec_ctrl.c              | 12 ++--
 xen/arch/x86/x86_64/mmconfig-shared.c |  4 +-
 xen/common/efi/boot.c                 |  4 +-
 xen/common/kernel.c                   | 79 +++++++++++++++++++++------
 xen/drivers/cpufreq/cpufreq.c         |  6 +-
 xen/drivers/passthrough/iommu.c       | 28 +++++-----
 xen/drivers/passthrough/pci.c         |  4 +-
 xen/include/xen/lib.h                 |  7 +++
 11 files changed, 124 insertions(+), 85 deletions(-)

diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c
index b978e05613..2be61606b4 100644
--- a/xen/arch/x86/cpu/vpmu.c
+++ b/xen/arch/x86/cpu/vpmu.c
@@ -61,42 +61,31 @@ static unsigned vpmu_count;
 
 static DEFINE_PER_CPU(struct vcpu *, last_vcpu);
 
-static int parse_vpmu_param(const char *s, unsigned int len)
-{
-    if ( !*s || !len )
-        return 0;
-    if ( !strncmp(s, "bts", len) )
-        vpmu_features |= XENPMU_FEATURE_INTEL_BTS;
-    else if ( !strncmp(s, "ipc", len) )
-        vpmu_features |= XENPMU_FEATURE_IPC_ONLY;
-    else if ( !strncmp(s, "arch", len) )
-        vpmu_features |= XENPMU_FEATURE_ARCH_ONLY;
-    else
-        return 1;
-    return 0;
-}
-
 static int __init parse_vpmu_params(const char *s)
 {
-    const char *sep, *p = s;
+    const char *ss;
 
     switch ( parse_bool(s, NULL) )
     {
     case 0:
         break;
     default:
-        for ( ; ; )
-        {
-            sep = strchr(p, ',');
-            if ( sep == NULL )
-                sep = strchr(p, 0);
-            if ( parse_vpmu_param(p, sep - p) )
-                goto error;
-            if ( !*sep )
-                /* reached end of flags */
-                break;
-            p = sep + 1;
-        }
+        do {
+            ss = strchr(s, ',');
+            if ( !ss )
+                ss = strchr(s, '\0');
+
+            if ( !cmdline_strcmp(s, "bts") )
+                vpmu_features |= XENPMU_FEATURE_INTEL_BTS;
+            else if ( !cmdline_strcmp(s, "ipc") )
+                vpmu_features |= XENPMU_FEATURE_IPC_ONLY;
+            else if ( !cmdline_strcmp(s, "arch") )
+                vpmu_features |= XENPMU_FEATURE_ARCH_ONLY;
+            else
+                return -EINVAL;
+
+            s = ss + 1;
+        } while ( *ss );
         /* fall through */
     case 1:
         /* Default VPMU mode */
@@ -105,10 +94,6 @@ static int __init parse_vpmu_params(const char *s)
         break;
     }
     return 0;
-
- error:
-    printk("VPMU: unknown flags: %s - vpmu disabled!\n", s);
-    return -EINVAL;
 }
 
 void vpmu_lvtpc_update(uint32_t val)
diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 87ef2e801f..0ceb9b9a1c 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -70,12 +70,12 @@ static int __init parse_irq_vector_map_param(const char *s)
         if ( !ss )
             ss = strchr(s, '\0');
 
-        if ( !strncmp(s, "none", ss - s))
-            opt_irq_vector_map=OPT_IRQ_VECTOR_MAP_NONE;
-        else if ( !strncmp(s, "global", ss - s))
-            opt_irq_vector_map=OPT_IRQ_VECTOR_MAP_GLOBAL;
-        else if ( !strncmp(s, "per-device", ss - s))
-            opt_irq_vector_map=OPT_IRQ_VECTOR_MAP_PERDEV;
+        if ( !cmdline_strcmp(s, "none") )
+            opt_irq_vector_map = OPT_IRQ_VECTOR_MAP_NONE;
+        else if ( !cmdline_strcmp(s, "global") )
+            opt_irq_vector_map = OPT_IRQ_VECTOR_MAP_GLOBAL;
+        else if ( !cmdline_strcmp(s, "per-device") )
+            opt_irq_vector_map = OPT_IRQ_VECTOR_MAP_PERDEV;
         else
             rc = -EINVAL;
 
diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index 0ba8ef88d4..5866a261e3 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -591,13 +591,13 @@ static int __init parse_psr_param(const char *s)
         if ( val_delim > ss )
             val_delim = ss;
 
-        if ( *val_delim && !strncmp(s, "rmid_max", val_delim - s) )
+        if ( *val_delim && !cmdline_strcmp(s, "rmid_max") )
         {
             opt_rmid_max = simple_strtoul(val_delim + 1, &q, 0);
             if ( *q && *q != ',' )
                 rc = -EINVAL;
         }
-        else if ( *val_delim && !strncmp(s, "cos_max", val_delim - s) )
+        else if ( *val_delim && !cmdline_strcmp(s, "cos_max") )
         {
             opt_cos_max = simple_strtoul(val_delim + 1, &q, 0);
             if ( *q && *q != ',' )
diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index eb480c1f08..e641894f17 100644
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -83,11 +83,11 @@ static int __init parse_bti(const char *s)
         {
             s += 6;
 
-            if ( !strncmp(s, "retpoline", ss - s) )
+            if ( !cmdline_strcmp(s, "retpoline") )
                 opt_thunk = THUNK_RETPOLINE;
-            else if ( !strncmp(s, "lfence", ss - s) )
+            else if ( !cmdline_strcmp(s, "lfence") )
                 opt_thunk = THUNK_LFENCE;
-            else if ( !strncmp(s, "jmp", ss - s) )
+            else if ( !cmdline_strcmp(s, "jmp") )
                 opt_thunk = THUNK_JMP;
             else
                 rc = -EINVAL;
@@ -194,11 +194,11 @@ static int __init parse_spec_ctrl(const char *s)
         {
             s += 10;
 
-            if ( !strncmp(s, "retpoline", ss - s) )
+            if ( !cmdline_strcmp(s, "retpoline") )
                 opt_thunk = THUNK_RETPOLINE;
-            else if ( !strncmp(s, "lfence", ss - s) )
+            else if ( !cmdline_strcmp(s, "lfence") )
                 opt_thunk = THUNK_LFENCE;
-            else if ( !strncmp(s, "jmp", ss - s) )
+            else if ( !cmdline_strcmp(s, "jmp") )
                 opt_thunk = THUNK_JMP;
             else
                 rc = -EINVAL;
diff --git a/xen/arch/x86/x86_64/mmconfig-shared.c b/xen/arch/x86/x86_64/mmconfig-shared.c
index 7c3b7fd30b..01b5720445 100644
--- a/xen/arch/x86/x86_64/mmconfig-shared.c
+++ b/xen/arch/x86/x86_64/mmconfig-shared.c
@@ -46,8 +46,8 @@ static int __init parse_mmcfg(const char *s)
         case 1:
             break;
         default:
-            if ( !strncmp(s, "amd_fam10", ss - s) ||
-                 !strncmp(s, "amd-fam10", ss - s) )
+            if ( !cmdline_strcmp(s, "amd_fam10") ||
+                 !cmdline_strcmp(s, "amd-fam10") )
                 pci_probe |= PCI_CHECK_ENABLE_AMD_MMCONF;
             else
                 rc = -EINVAL;
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 6be0b3986f..a9917f31f1 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1323,14 +1323,14 @@ static int __init parse_efi_param(const char *s)
         if ( !ss )
             ss = strchr(s, '\0');
 
-        if ( !strncmp(s, "rs", ss - s) )
+        if ( !cmdline_strcmp(s, "rs") )
         {
             if ( val )
                 __set_bit(EFI_RS, &efi_flags);
             else
                 __clear_bit(EFI_RS, &efi_flags);
         }
-        else if ( !strncmp(s, "attr=uc", ss - s) )
+        else if ( !cmdline_strcmp(s, "attr=uc") )
             efi_map_uc = val;
         else
             rc = -EINVAL;
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 5766a0f784..053c31d391 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -221,25 +221,51 @@ void __init cmdline_parse(const char *cmdline)
 
 int parse_bool(const char *s, const char *e)
 {
-    unsigned int len;
+    size_t len = e ? ({ ASSERT(e >= s); e - s; }) : strlen(s);
 
-    len = e ? ({ ASSERT(e >= s); e - s; }) : strlen(s);
-    if ( !len )
-        return -1;
+    switch ( len )
+    {
+    case 1:
+        if ( *s == '1' )
+            return 1;
+        if ( *s == '0' )
+            return 0;
+        break;
 
-    if ( !strncmp("no", s, len) ||
-         !strncmp("off", s, len) ||
-         !strncmp("false", s, len) ||
-         !strncmp("disable", s, len) ||
-         !strncmp("0", s, len) )
-        return 0;
+    case 2:
+        if ( !strncmp("on", s, 2) )
+            return 1;
+        if ( !strncmp("no", s, 2) )
+            return 0;
+        break;
+
+    case 3:
+        if ( !strncmp("yes", s, 3) )
+            return 1;
+        if ( !strncmp("off", s, 3) )
+            return 0;
+        break;
+
+    case 4:
+        if ( !strncmp("true", s, 4) )
+            return 1;
+        break;
+
+    case 5:
+        if ( !strncmp("false", s, 5) )
+            return 0;
+        break;
 
-    if ( !strncmp("yes", s, len) ||
-         !strncmp("on", s, len) ||
-         !strncmp("true", s, len) ||
-         !strncmp("enable", s, len) ||
-         !strncmp("1", s, len) )
-        return 1;
+    case 6:
+        if ( !strncmp("enable", s, 6) )
+            return 1;
+        break;
+
+    case 7:
+        if ( !strncmp("disable", s, 7) )
+            return 0;
+        break;
+    }
 
     return -1;
 }
@@ -271,6 +297,27 @@ int parse_boolean(const char *name, const char *s, const char *e)
     return -1;
 }
 
+int cmdline_strcmp(const char *frag, const char *name)
+{
+    for ( ; ; frag++, name++ )
+    {
+        unsigned char f = *frag, n = *name;
+        int res = f - n;
+
+        if ( res || n == '\0' )
+        {
+            /*
+             * NUL in 'name' matching a comma, colon or semicolon in 'frag'
+             * implies success.
+             */
+            if ( n == '\0' && (f == ',' || f == ':' || f == ';') )
+                res = 0;
+
+            return res;
+        }
+    }
+}
+
 unsigned int tainted;
 
 /**
diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c
index 212f48f9f4..6152a045d9 100644
--- a/xen/drivers/cpufreq/cpufreq.c
+++ b/xen/drivers/cpufreq/cpufreq.c
@@ -73,7 +73,7 @@ static int __init setup_cpufreq_option(const char *str)
         arg = strchr(str, '\0');
     choice = parse_bool(str, arg);
 
-    if ( choice < 0 && !strncmp(str, "dom0-kernel", arg - str) )
+    if ( choice < 0 && !cmdline_strcmp(str, "dom0-kernel") )
     {
         xen_processor_pmbits &= ~XEN_PROCESSOR_PM_PX;
         cpufreq_controller = FREQCTL_dom0_kernel;
@@ -81,14 +81,14 @@ static int __init setup_cpufreq_option(const char *str)
         return 0;
     }
 
-    if ( choice == 0 || !strncmp(str, "none", arg - str) )
+    if ( choice == 0 || !cmdline_strcmp(str, "none") )
     {
         xen_processor_pmbits &= ~XEN_PROCESSOR_PM_PX;
         cpufreq_controller = FREQCTL_none;
         return 0;
     }
 
-    if ( choice > 0 || !strncmp(str, "xen", arg - str) )
+    if ( choice > 0 || !cmdline_strcmp(str, "xen") )
     {
         xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
         cpufreq_controller = FREQCTL_xen;
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 2c44fabf99..f9b13b018c 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -95,36 +95,36 @@ static int __init parse_iommu_param(const char *s)
         b = parse_bool(s, ss);
         if ( b >= 0 )
             iommu_enable = b;
-        else if ( !strncmp(s, "force", ss - s) ||
-                  !strncmp(s, "required", ss - s) )
+        else if ( !cmdline_strcmp(s, "force") ||
+                  !cmdline_strcmp(s, "required") )
             force_iommu = val;
-        else if ( !strncmp(s, "workaround_bios_bug", ss - s) )
+        else if ( !cmdline_strcmp(s, "workaround_bios_bug") )
             iommu_workaround_bios_bug = val;
-        else if ( !strncmp(s, "igfx", ss - s) )
+        else if ( !cmdline_strcmp(s, "igfx") )
             iommu_igfx = val;
-        else if ( !strncmp(s, "verbose", ss - s) )
+        else if ( !cmdline_strcmp(s, "verbose") )
             iommu_verbose = val;
-        else if ( !strncmp(s, "snoop", ss - s) )
+        else if ( !cmdline_strcmp(s, "snoop") )
             iommu_snoop = val;
-        else if ( !strncmp(s, "qinval", ss - s) )
+        else if ( !cmdline_strcmp(s, "qinval") )
             iommu_qinval = val;
-        else if ( !strncmp(s, "intremap", ss - s) )
+        else if ( !cmdline_strcmp(s, "intremap") )
             iommu_intremap = val;
-        else if ( !strncmp(s, "intpost", ss - s) )
+        else if ( !cmdline_strcmp(s, "intpost") )
             iommu_intpost = val;
-        else if ( !strncmp(s, "debug", ss - s) )
+        else if ( !cmdline_strcmp(s, "debug") )
         {
             iommu_debug = val;
             if ( val )
                 iommu_verbose = 1;
         }
-        else if ( !strncmp(s, "amd-iommu-perdev-intremap", ss - s) )
+        else if ( !cmdline_strcmp(s, "amd-iommu-perdev-intremap") )
             amd_iommu_perdev_intremap = val;
-        else if ( !strncmp(s, "dom0-passthrough", ss - s) )
+        else if ( !cmdline_strcmp(s, "dom0-passthrough") )
             iommu_passthrough = val;
-        else if ( !strncmp(s, "dom0-strict", ss - s) )
+        else if ( !cmdline_strcmp(s, "dom0-strict") )
             iommu_dom0_strict = val;
-        else if ( !strncmp(s, "sharept", ss - s) )
+        else if ( !cmdline_strcmp(s, "sharept") )
             iommu_hap_pt_share = val;
         else
             rc = -EINVAL;
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 1db69d5b99..f51cae7f4e 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -212,12 +212,12 @@ static int __init parse_pci_param(const char *s)
         if ( !ss )
             ss = strchr(s, '\0');
 
-        if ( !strncmp(s, "serr", ss - s) )
+        if ( !cmdline_strcmp(s, "serr") )
         {
             cmd_mask = PCI_COMMAND_SERR;
             brctl_mask = PCI_BRIDGE_CTL_SERR | PCI_BRIDGE_CTL_DTMR_SERR;
         }
-        else if ( !strncmp(s, "perr", ss - s) )
+        else if ( !cmdline_strcmp(s, "perr") )
         {
             cmd_mask = PCI_COMMAND_PARITY;
             brctl_mask = PCI_BRIDGE_CTL_PARITY;
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index 1d9771340c..750f809968 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -81,6 +81,13 @@ int parse_bool(const char *s, const char *e);
  */
 int parse_boolean(const char *name, const char *s, const char *e);
 
+/**
+ * Very similar to strcmp(), but will declare a match if the NUL in 'name'
+ * lines up with comma, colon or semicolon in 'frag'.  Designed for picking
+ * exact string matches out of a delimited command line list.
+ */
+int cmdline_strcmp(const char *frag, const char *name);
+
 /*#define DEBUG_TRACE_DUMP*/
 #ifdef DEBUG_TRACE_DUMP
 extern void debugtrace_dump(void);
-- 
2.20.1