From: Mark Wielaard <mark@klomp.org>
Date: Thu, 8 May 2025 22:21:25 +0000 (+0200)
Subject: mount syscall param filesystemtype may be NULL
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ff6e14ab798af0628c54c6a704c1cb8844a79419;p=thirdparty%2Fvalgrind.git

mount syscall param filesystemtype may be NULL

On Linux the mount syscall, depending on flags provided, the source,
type and data my be ignored.  We already don't check data and allow
source to be NULL.  Normally when type is ignored an application will
provide an empty string "".  But sometimes NULL is passed (like for
source).  So we now also allow type to be NULL to prevent false
positives.

Adjust the linux/scalar.c tests so the type param is still
unaddressable.

https://bugs.kde.org/show_bug.cgi?id=503914
---

diff --git a/NEWS b/NEWS
index 7c66ec08b..1ced90cae 100644
--- a/NEWS
+++ b/NEWS
@@ -26,6 +26,7 @@ are not entered into bugzilla tend to get forgotten about or ignored.
 503641  close_range syscalls started failing with 3.25.0
 503677  duplicated-cond compiler warning in dis_RV64M
 503817  s390x: fix 'ordered comparison of pointer with integer zero' compiler warnings
+503914  mount syscall param filesystemtype may be NULL
 
 To see details of a given bug, visit
   https://bugs.kde.org/show_bug.cgi?id=XXXXXX
diff --git a/coregrind/m_syswrap/syswrap-linux.c b/coregrind/m_syswrap/syswrap-linux.c
index 6f3917830..afd4a618b 100644
--- a/coregrind/m_syswrap/syswrap-linux.c
+++ b/coregrind/m_syswrap/syswrap-linux.c
@@ -1000,7 +1000,8 @@ PRE(sys_mount)
 {
    // Nb: depending on 'flags', the 'type' and 'data' args may be ignored.
    // We are conservative and check everything, except the memory pointed to
-   // by 'data'.
+   // by 'data'. And since both 'source' and 'type' may be ignored, we allow
+   // them to be NULL.
    *flags |= SfMayBlock;
    PRINT("sys_mount( %#" FMT_REGWORD "x(%s), %#" FMT_REGWORD "x(%s), %#"
          FMT_REGWORD "x(%s), %#" FMT_REGWORD "x, %#" FMT_REGWORD "x )",
@@ -1012,7 +1013,8 @@ PRE(sys_mount)
    if (ARG1)
       PRE_MEM_RASCIIZ( "mount(source)", ARG1);
    PRE_MEM_RASCIIZ( "mount(target)", ARG2);
-   PRE_MEM_RASCIIZ( "mount(type)", ARG3);
+   if (ARG3)
+      PRE_MEM_RASCIIZ( "mount(type)", ARG3);
 }
 
 PRE(sys_oldumount)
diff --git a/memcheck/tests/arm64-linux/scalar.c b/memcheck/tests/arm64-linux/scalar.c
index 622ea1c47..49e0ca6a7 100644
--- a/memcheck/tests/arm64-linux/scalar.c
+++ b/memcheck/tests/arm64-linux/scalar.c
@@ -128,7 +128,7 @@ int main(void)
 
    // __NR_mount 21
    GO(__NR_mount, "5s 3m");
-   SY(__NR_mount, x0, x0, x0, x0, x0); FAIL;
+   SY(__NR_mount, x0, x0, x0-1, x0, x0); FAIL;
    
    // __NR_umount arm64 only has umount2
    //GO(__NR_umount, "1s 1m");
diff --git a/memcheck/tests/x86-linux/scalar.c b/memcheck/tests/x86-linux/scalar.c
index 83ed38c4d..fe36a47ef 100644
--- a/memcheck/tests/x86-linux/scalar.c
+++ b/memcheck/tests/x86-linux/scalar.c
@@ -137,7 +137,7 @@ int main(void)
 
    // __NR_mount 21
    GO(__NR_mount, "5s 3m");
-   SY(__NR_mount, x0, x0, x0, x0, x0); FAIL;
+   SY(__NR_mount, x0, x0, x0-1, x0, x0); FAIL;
    
    // __NR_umount 22
    GO(__NR_umount, "1s 1m");