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>
Release-acked-by: Juergen Gross <jgross@suse.com>

diff --git a/xen/arch/arm/cpuerrata.c b/xen/arch/arm/cpuerrata.c
index adf88e7bdcf8b025671f2fda31157f201ac8a9c2..f4815cafb4db3f56f042f13b1cf5f7e8c14bb08a 100644 (file)
--- a/xen/arch/arm/cpuerrata.c
+++ b/xen/arch/arm/cpuerrata.c
@@ -257,11 +257,11 @@ static int __init parse_spec_ctrl(const char *s)
         {
             s += 5;
 
-            if ( !strncmp(s, "force-disable", ss - s) )
+            if ( !cmdline_strcmp(s, "force-disable") )
                 ssbd_state = ARM_SSBD_FORCE_DISABLE;
-            else if ( !strncmp(s, "runtime", ss - s) )
+            else if ( !cmdline_strcmp(s, "runtime") )
                 ssbd_state = ARM_SSBD_RUNTIME;
-            else if ( !strncmp(s, "force-enable", ss - s) )
+            else if ( !cmdline_strcmp(s, "force-enable") )
                 ssbd_state = ARM_SSBD_FORCE_ENABLE;
             else
                 rc = -EINVAL;

diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c
index 8a4f753eae90e490103b9253ce67cea159137fe2..13da7d0a6856b019aae4b078b107985c09b3454d 100644 (file)
--- 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 8b44d6ce0b86b0ea210a4b26484ea4ddf05deedc..23b4f423e660ef4f0d60fefec9942a246c8d64f0 100644 (file)
--- 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 0ba8ef88d402ca5ab3f70cf96703837832e1e1c5..5866a261e3de3cda2289197b163588a8f515334e 100644 (file)
--- 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 a36bcef6ca68b28848075aca2609d83a40fa3886..ad72ecd3a5446dcdc2c7c10e183032c1aa55c934 100644 (file)
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -138,11 +138,11 @@ 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 8675dbd1eddc65e9e9ca16b89624aa429d509d96..9e1c81dcd29c20f387f9b2a138a3924b573e8ad5 100644 (file)
--- 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 2ed540364d2d4ad5b6b7e73573852450f878d32e..1e1a5517321d1307d7e66c77c10c9aaa49034e9d 100644 (file)
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1401,14 +1401,14 @@ 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 5766a0f784eb2525a6da10b7577aa7ab126a0369..053c31d39158a5e894444f68c15cb84a316171b5 100644 (file)
--- 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 4d6badc66334f66cca7b6dc4afe671e7de6b8577..ba9897a22be90bed9a36139899ac5b879ebade81 100644 (file)
--- 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 b06393d17dc0ef45d3441f5387de47c0e726927e..bd1af35a13895b4e1c1b70d1d7dfd9aa5faae743 100644 (file)
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -98,36 +98,36 @@ 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_hwdom_passthrough = val;
-        else if ( !strncmp(s, "dom0-strict", ss - s) )
+        else if ( !cmdline_strcmp(s, "dom0-strict") )
             iommu_hwdom_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 1277ce2a0ffa88c9b5e78e85e3b0aad7ae075421..93c20b9b064a6ab57eeab0c820c02259e95c5f02 100644 (file)
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -213,12 +213,12 @@ 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 972fc843fa894274cef8fef3ac439a67ef805416..89939f43c8dd542de0969392971dc95a68dc1ef7 100644 (file)
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -79,6 +79,13 @@ 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);