net/tap-win32.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
Simply increase destination buffer size so truncation can't happen.
"cc" "-m64" "-Ilibcommon.a.p" "-Isubprojects/dtc/libfdt" "-I../subprojects/dtc/libfdt" "-ID:/a/_temp/msys64/mingw64/include/pixman-1" "-ID:/a/_temp/msys64/mingw64/include/glib-2.0" "-ID:/a/_temp/msys64/mingw64/lib/glib-2.0/include" "-ID:/a/_temp/msys64/mingw64/include/ncursesw" "-fdiagnostics-color=auto" "-Wall" "-Winvalid-pch" "-Werror" "-std=gnu11" "-O2" "-g" "-fstack-protector-strong" "-Wempty-body" "-Wendif-labels" "-Wexpansion-to-defined" "-Wformat-security" "-Wformat-y2k" "-Wignored-qualifiers" "-Wimplicit-fallthrough=2" "-Winit-self" "-Wmissing-format-attribute" "-Wmissing-prototypes" "-Wnested-externs" "-Wold-style-declaration" "-Wold-style-definition" "-Wredundant-decls" "-Wshadow=local" "-Wstrict-prototypes" "-Wtype-limits" "-Wundef" "-Wvla" "-Wwrite-strings" "-Wno-missing-include-dirs" "-Wno-psabi" "-Wno-shift-negative-value" "-iquote" "." "-iquote" "D:/a/qemu/qemu" "-iquote" "D:/a/qemu/qemu/include" "-iquote" "D:/a/qemu/qemu/host/include/x86_64" "-iquote" "D:/a/qemu/qemu/host/include/generic" "-iq
../net/tap-win32.c: In function 'tap_win32_open':
../net/tap-win32.c:343:19: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size 176 [-Werror=format-truncation=]
343 | "%s\\%s\\Connection",
| ^~
344 | NETWORK_CONNECTIONS_KEY, enum_name);
| ~~~~~~~~~
In function 'get_device_guid',
inlined from 'tap_win32_open' at ../net/tap-win32.c:616:10:
../net/tap-win32.c:341:9: note: 'snprintf' output between 92 and 347 bytes into a destination of size 256
341 | snprintf(connection_string,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
342 | sizeof(connection_string),
| ~~~~~~~~~~~~~~~~~~~~~~~~~~
343 | "%s\\%s\\Connection",
| ~~~~~~~~~~~~~~~~~~~~~
344 | NETWORK_CONNECTIONS_KEY, enum_name);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../net/tap-win32.c: In function 'tap_win32_open':
../net/tap-win32.c:242:58: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size 178 [-Werror=format-truncation=]
242 | snprintf (unit_string, sizeof(unit_string), "%s\\%s",
| ^~
243 | ADAPTER_KEY, enum_name);
| ~~~~~~~~~
In function 'is_tap_win32_dev',
inlined from 'get_device_guid' at ../net/tap-win32.c:368:21,
inlined from 'tap_win32_open' at ../net/tap-win32.c:616:10:
../net/tap-win32.c:242:9: note: 'snprintf' output between 79 and 334 bytes into a destination of size 256
242 | snprintf (unit_string, sizeof(unit_string), "%s\\%s",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
243 | ADAPTER_KEY, enum_name);
| ~~~~~~~~~~~~~~~~~~~~~~~
../net/tap-win32.c: In function 'tap_win32_open':
../net/tap-win32.c:620:52: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size 245 [-Werror=format-truncation=]
620 | snprintf (device_path, sizeof(device_path), "%s%s%s",
| ^~
621 | USERMODEDEVICEDIR,
622 | device_guid,
| ~~~~~~~~~~~
../net/tap-win32.c:620:5: note: 'snprintf' output between 16 and 271 bytes into a destination of size 256
620 | snprintf (device_path, sizeof(device_path), "%s%s%s",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
621 | USERMODEDEVICEDIR,
| ~~~~~~~~~~~~~~~~~~
622 | device_guid,
| ~~~~~~~~~~~~
623 | TAPSUFFIX);
| ~~~~~~~~~~
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
---
net/tap-win32.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/tap-win32.c b/net/tap-win32.c
index 7edbd716337..4a4625af2b2 100644
--- a/net/tap-win32.c
+++ b/net/tap-win32.c
@@ -214,7 +214,7 @@ static int is_tap_win32_dev(const char *guid)
for (;;) {
char enum_name[256];
- char unit_string[256];
+ char unit_string[512];
HKEY unit_key;
char component_id_string[] = "ComponentId";
char component_id[256];
@@ -315,7 +315,7 @@ static int get_device_guid(
while (!stop)
{
char enum_name[256];
- char connection_string[256];
+ char connection_string[512];
HKEY connection_key;
char name_data[256];
DWORD name_type;
@@ -595,7 +595,7 @@ static void tap_win32_free_buffer(tap_win32_overlapped_t *overlapped,
static int tap_win32_open(tap_win32_overlapped_t **phandle,
const char *preferred_name)
{
- char device_path[256];
+ char device_path[512];
char device_guid[0x100];
int rc;
HANDLE handle;
--
2.39.5Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
> Simply increase destination buffer size so truncation can't happen.
>
> "cc" "-m64" "-Ilibcommon.a.p" "-Isubprojects/dtc/libfdt"
> "-I../subprojects/dtc/libfdt"
> "-ID:/a/_temp/msys64/mingw64/include/pixman-1"
> "-ID:/a/_temp/msys64/mingw64/include/glib-2.0"
> "-ID:/a/_temp/msys64/mingw64/lib/glib-2.0/include"
> "-ID:/a/_temp/msys64/mingw64/include/ncursesw"
> "-fdiagnostics-color=auto" "-Wall" "-Winvalid-pch" "-Werror"
> "-std=gnu11" "-O2" "-g" "-fstack-protector-strong" "-Wempty-body"
> "-Wendif-labels" "-Wexpansion-to-defined" "-Wformat-security"
> "-Wformat-y2k" "-Wignored-qualifiers" "-Wimplicit-fallthrough=2"
> "-Winit-self" "-Wmissing-format-attribute" "-Wmissing-prototypes"
> "-Wnested-externs" "-Wold-style-declaration" "-Wold-style-definition"
> "-Wredundant-decls" "-Wshadow=local" "-Wstrict-prototypes"
> "-Wtype-limits" "-Wundef" "-Wvla" "-Wwrite-strings"
> "-Wno-missing-include-dirs" "-Wno-psabi" "-Wno-shift-negative-value"
> "-iquote" "." "-iquote" "D:/a/qemu/qemu" "-iquote"
> "D:/a/qemu/qemu/include" "-iquote"
> "D:/a/qemu/qemu/host/include/x86_64" "-iquote"
> "D:/a/qemu/qemu/host/include/generic" "-iq
> ../net/tap-win32.c: In function 'tap_win32_open':
> ../net/tap-win32.c:343:19: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size 176 [-Werror=format-truncation=]
> 343 | "%s\\%s\\Connection",
> | ^~
> 344 | NETWORK_CONNECTIONS_KEY, enum_name);
> | ~~~~~~~~~
> In function 'get_device_guid',
> inlined from 'tap_win32_open' at ../net/tap-win32.c:616:10:
> ../net/tap-win32.c:341:9: note: 'snprintf' output between 92 and 347
> bytes into a destination of size 256
Is the compiler min/max maxing what UCS-16 or UTF-8 might pack into that string?
>
> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> ---
> net/tap-win32.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/tap-win32.c b/net/tap-win32.c
> index 7edbd716337..4a4625af2b2 100644
> --- a/net/tap-win32.c
> +++ b/net/tap-win32.c
> @@ -214,7 +214,7 @@ static int is_tap_win32_dev(const char *guid)
>
> for (;;) {
> char enum_name[256];
> - char unit_string[256];
> + char unit_string[512];
If this isn't perf sensitive code lets just get rid of this stack
allocation and be done with some autofree'd g_strdup_printfs?
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
On 10/23/24 12:50, Alex Bennée wrote:
> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
>
>> Simply increase destination buffer size so truncation can't happen.
>>
>> "cc" "-m64" "-Ilibcommon.a.p" "-Isubprojects/dtc/libfdt"
>> "-I../subprojects/dtc/libfdt"
>> "-ID:/a/_temp/msys64/mingw64/include/pixman-1"
>> "-ID:/a/_temp/msys64/mingw64/include/glib-2.0"
>> "-ID:/a/_temp/msys64/mingw64/lib/glib-2.0/include"
>> "-ID:/a/_temp/msys64/mingw64/include/ncursesw"
>> "-fdiagnostics-color=auto" "-Wall" "-Winvalid-pch" "-Werror"
>> "-std=gnu11" "-O2" "-g" "-fstack-protector-strong" "-Wempty-body"
>> "-Wendif-labels" "-Wexpansion-to-defined" "-Wformat-security"
>> "-Wformat-y2k" "-Wignored-qualifiers" "-Wimplicit-fallthrough=2"
>> "-Winit-self" "-Wmissing-format-attribute" "-Wmissing-prototypes"
>> "-Wnested-externs" "-Wold-style-declaration" "-Wold-style-definition"
>> "-Wredundant-decls" "-Wshadow=local" "-Wstrict-prototypes"
>> "-Wtype-limits" "-Wundef" "-Wvla" "-Wwrite-strings"
>> "-Wno-missing-include-dirs" "-Wno-psabi" "-Wno-shift-negative-value"
>> "-iquote" "." "-iquote" "D:/a/qemu/qemu" "-iquote"
>> "D:/a/qemu/qemu/include" "-iquote"
>> "D:/a/qemu/qemu/host/include/x86_64" "-iquote"
>> "D:/a/qemu/qemu/host/include/generic" "-iq
>> ../net/tap-win32.c: In function 'tap_win32_open':
>> ../net/tap-win32.c:343:19: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size 176 [-Werror=format-truncation=]
>> 343 | "%s\\%s\\Connection",
>> | ^~
>> 344 | NETWORK_CONNECTIONS_KEY, enum_name);
>> | ~~~~~~~~~
>> In function 'get_device_guid',
>> inlined from 'tap_win32_open' at ../net/tap-win32.c:616:10:
>> ../net/tap-win32.c:341:9: note: 'snprintf' output between 92 and 347
>> bytes into a destination of size 256
>
> Is the compiler min/max maxing what UCS-16 or UTF-8 might pack into that string?
>>
Yes, enum_name (used to compose final string) is already sized 256, so
result *may* be bigger. I'm not sure it would happen in the real world
though.
The result strings are used to access registry keys, which have a max
size of 255. And device_path is used to open a file, which is limited in
size too.
https://learn.microsoft.com/en-us/windows/win32/sysinfo/registry-element-size-limits
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> ---
>> net/tap-win32.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/tap-win32.c b/net/tap-win32.c
>> index 7edbd716337..4a4625af2b2 100644
>> --- a/net/tap-win32.c
>> +++ b/net/tap-win32.c
>> @@ -214,7 +214,7 @@ static int is_tap_win32_dev(const char *guid)
>>
>> for (;;) {
>> char enum_name[256];
>> - char unit_string[256];
>> + char unit_string[512];
>
> If this isn't perf sensitive code lets just get rid of this stack
> allocation and be done with some autofree'd g_strdup_printfs?
>
Yes, will do that.
All this is used only when opening the device, so it's not on any hot path.
Thanks,
Pierrick
On 10/23/24 13:15, Pierrick Bouvier wrote: > On 10/23/24 12:50, Alex Bennée wrote: >> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes: >> >>> Simply increase destination buffer size so truncation can't happen. >>> >>> "cc" "-m64" "-Ilibcommon.a.p" "-Isubprojects/dtc/libfdt" >>> "-I../subprojects/dtc/libfdt" >>> "-ID:/a/_temp/msys64/mingw64/include/pixman-1" >>> "-ID:/a/_temp/msys64/mingw64/include/glib-2.0" >>> "-ID:/a/_temp/msys64/mingw64/lib/glib-2.0/include" >>> "-ID:/a/_temp/msys64/mingw64/include/ncursesw" >>> "-fdiagnostics-color=auto" "-Wall" "-Winvalid-pch" "-Werror" >>> "-std=gnu11" "-O2" "-g" "-fstack-protector-strong" "-Wempty-body" >>> "-Wendif-labels" "-Wexpansion-to-defined" "-Wformat-security" >>> "-Wformat-y2k" "-Wignored-qualifiers" "-Wimplicit-fallthrough=2" >>> "-Winit-self" "-Wmissing-format-attribute" "-Wmissing-prototypes" >>> "-Wnested-externs" "-Wold-style-declaration" "-Wold-style-definition" >>> "-Wredundant-decls" "-Wshadow=local" "-Wstrict-prototypes" >>> "-Wtype-limits" "-Wundef" "-Wvla" "-Wwrite-strings" >>> "-Wno-missing-include-dirs" "-Wno-psabi" "-Wno-shift-negative-value" >>> "-iquote" "." "-iquote" "D:/a/qemu/qemu" "-iquote" >>> "D:/a/qemu/qemu/include" "-iquote" >>> "D:/a/qemu/qemu/host/include/x86_64" "-iquote" >>> "D:/a/qemu/qemu/host/include/generic" "-iq >>> ../net/tap-win32.c: In function 'tap_win32_open': >>> ../net/tap-win32.c:343:19: error: '%s' directive output may be truncated writing up to >>> 255 bytes into a region of size 176 [-Werror=format-truncation=] >>> 343 | "%s\\%s\\Connection", >>> | ^~ >>> 344 | NETWORK_CONNECTIONS_KEY, enum_name); >>> | ~~~~~~~~~ >>> In function 'get_device_guid', >>> inlined from 'tap_win32_open' at ../net/tap-win32.c:616:10: >>> ../net/tap-win32.c:341:9: note: 'snprintf' output between 92 and 347 >>> bytes into a destination of size 256 >> >> Is the compiler min/max maxing what UCS-16 or UTF-8 might pack into that string? >>> > > Yes, enum_name (used to compose final string) is already sized 256, so result *may* be > bigger. I'm not sure it would happen in the real world though. There are several patches for this, most recently: https://lore.kernel.org/qemu-devel/20241008202842.4478-1-shentey@gmail.com/ r~
On 10/23/24 14:30, Richard Henderson wrote: > On 10/23/24 13:15, Pierrick Bouvier wrote: >> On 10/23/24 12:50, Alex Bennée wrote: >>> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes: >>> >>>> Simply increase destination buffer size so truncation can't happen. >>>> >>>> "cc" "-m64" "-Ilibcommon.a.p" "-Isubprojects/dtc/libfdt" >>>> "-I../subprojects/dtc/libfdt" >>>> "-ID:/a/_temp/msys64/mingw64/include/pixman-1" >>>> "-ID:/a/_temp/msys64/mingw64/include/glib-2.0" >>>> "-ID:/a/_temp/msys64/mingw64/lib/glib-2.0/include" >>>> "-ID:/a/_temp/msys64/mingw64/include/ncursesw" >>>> "-fdiagnostics-color=auto" "-Wall" "-Winvalid-pch" "-Werror" >>>> "-std=gnu11" "-O2" "-g" "-fstack-protector-strong" "-Wempty-body" >>>> "-Wendif-labels" "-Wexpansion-to-defined" "-Wformat-security" >>>> "-Wformat-y2k" "-Wignored-qualifiers" "-Wimplicit-fallthrough=2" >>>> "-Winit-self" "-Wmissing-format-attribute" "-Wmissing-prototypes" >>>> "-Wnested-externs" "-Wold-style-declaration" "-Wold-style-definition" >>>> "-Wredundant-decls" "-Wshadow=local" "-Wstrict-prototypes" >>>> "-Wtype-limits" "-Wundef" "-Wvla" "-Wwrite-strings" >>>> "-Wno-missing-include-dirs" "-Wno-psabi" "-Wno-shift-negative-value" >>>> "-iquote" "." "-iquote" "D:/a/qemu/qemu" "-iquote" >>>> "D:/a/qemu/qemu/include" "-iquote" >>>> "D:/a/qemu/qemu/host/include/x86_64" "-iquote" >>>> "D:/a/qemu/qemu/host/include/generic" "-iq >>>> ../net/tap-win32.c: In function 'tap_win32_open': >>>> ../net/tap-win32.c:343:19: error: '%s' directive output may be truncated writing up to >>>> 255 bytes into a region of size 176 [-Werror=format-truncation=] >>>> 343 | "%s\\%s\\Connection", >>>> | ^~ >>>> 344 | NETWORK_CONNECTIONS_KEY, enum_name); >>>> | ~~~~~~~~~ >>>> In function 'get_device_guid', >>>> inlined from 'tap_win32_open' at ../net/tap-win32.c:616:10: >>>> ../net/tap-win32.c:341:9: note: 'snprintf' output between 92 and 347 >>>> bytes into a destination of size 256 >>> >>> Is the compiler min/max maxing what UCS-16 or UTF-8 might pack into that string? >>>> >> >> Yes, enum_name (used to compose final string) is already sized 256, so result *may* be >> bigger. I'm not sure it would happen in the real world though. > > There are several patches for this, most recently: > > https://lore.kernel.org/qemu-devel/20241008202842.4478-1-shentey@gmail.com/ > > > r~ Thanks for pointing it Richard. The linked patch is better than current approach, so it should be favored. Regards, Pierrick
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