[PATCH] Linux: Also check for 0 return value from vDSO gerandom probe

[Florian Weimer]

As of Linux 6.13, there is no code in the vDSO that declines this
initialization request with the special ~0UL state size.  If the vDSO
has the function, the call succeeds and returns 0.  It's expected
that the code would follow the “a negative value indicating an error”
convention, as indicated in the __cvdso_getrandom_data function
comment, so that INTERNAL_SYSCALL_ERROR_P on glibc's side would return
true.  Yet this commit treats all non-zero values as error indicators.

Fixes commit 4f5704ea347e52ac3f272d1341da10aed6e9973e ("powerpc: Use
correct procedure call standard for getrandom vDSO call (bug 32440)").

Tested on x86_64-linux-gnu.

---
 sysdeps/unix/sysv/linux/getrandom.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/unix/sysv/linux/getrandom.c b/sysdeps/unix/sysv/linux/getrandom.c
index 0dc8fa6e65..815f4b1f4a 100644
--- a/sysdeps/unix/sysv/linux/getrandom.c
+++ b/sysdeps/unix/sysv/linux/getrandom.c
@@ -246,7 +246,7 @@ __getrandom_early_init (_Bool initial)
       } params;
       long int ret = INTERNAL_VSYSCALL_CALL (GLRO(dl_vdso_getrandom),
 					     5, NULL, 0, 0, &params, ~0UL);
-      if (! INTERNAL_SYSCALL_ERROR_P (ret))
+      if (! INTERNAL_SYSCALL_ERROR_P (ret) && ret == 0)
 	{
 	  /* Align each opaque state to L1 data cache size to avoid false
 	     sharing.  If the size can not be obtained, use the kernel

base-commit: 20f8c5df56f68a783ceab59d2d77184e32a28ff4