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

(cherry picked from commit ff6e14ab798af0628c54c6a704c1cb8844a79419)

diff --git a/NEWS b/NEWS
index 7cbe6344ac4017ed42a599d1e90009a8357936bd..3f084a52be09749b9f7dbaca915ee899aba3f26c 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,7 @@ Branch 3.25
 The following bugs have been fixed or resolved on this branch.
 
 503641  close_range syscalls started failing with 3.25.0
+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 6f3917830fa4771a6688fe8da11f448da66cdcf3..afd4a618b12f7f76a84a5044f7432e44592d1e77 100644 (file)
--- 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 622ea1c47cc9ccf128a16bebba4aa6075fbe427f..49e0ca6a701f344bf64436a047f76e3b2a21e6d0 100644 (file)
--- 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 83ed38c4d994a9d3bbc51c16df86144f9f59a460..fe36a47ef0f58d8f824983cafe90a8f6ed366347 100644 (file)
--- 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");