[glibc] alpha: fix setrlimit compat symbol for negative rlim values besides -1

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c056561d31a29d82d89b5a374aea3147fd5a2de3

commit c056561d31a29d82d89b5a374aea3147fd5a2de3
Author: Matt Turner <[email protected]>
Date:   Sat May 23 12:53:05 2026 -0400

    alpha: fix setrlimit compat symbol for negative rlim values besides -1
    
    Old alpha glibc defined rlim_t as signed long, making RLIM_INFINITY
    equal to LONG_MAX (0x7ffffffffffffffful).  The compat symbol
    __old_setrlimit64 (setrlimit@GLIBC_2.0 and setrlimit64@GLIBC_2.1) was
    introduced in 0d0bc784ca [BZ #22648] to translate this old RLIM_INFINITY
    to the kernel's RLIM64_INFINITY (ULONG_MAX) before the prlimit64
    syscall, using an exact equality check.
    
    Because old rlim_t was signed, any value a caller treats as negative
    (e.g. -2 = 0xfffffffffffffffe unsigned) is also an "infinity or beyond"
    value in the old ABI.  Such values are >= OLD_RLIM64_INFINITY and
    should be translated to RLIM64_INFINITY; passing them through unchanged
    causes prlimit64 to treat them as large finite limits, resulting in
    unexpected failures (EPERM or silent truncation).
    
    Change the equality check to >= OLD_RLIM64_INFINITY in
    __old_setrlimit64 so that all values the old signed-rlim_t ABI would
    interpret as infinity-or-more are correctly mapped to RLIM64_INFINITY.
    
    No change is made to __old_getrlimit64: prlimit64 returns only exact
    RLIM64_INFINITY for unlimited resources, so the existing equality
    check against RLIM64_INFINITY is correct and mirrors the kernel's own
    rlim64_is_infinity() logic.
    
    Fixes: 0d0bc784ca ("Alpha: Add wrappers to get/setrlimit64 to fix
    RLIM64_INFINITY constant [BZ #22648]")
    Fixes: https://sourceware.org/bugzilla/show_bug.cgi?id=30992
    Reviewed-by: Adhemerval Zanella <[email protected]>

Diff:
---
 sysdeps/unix/sysv/linux/alpha/setrlimit64.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/alpha/setrlimit64.c b/sysdeps/unix/sysv/linux/alpha/setrlimit64.c
index 512aaf2042..d8cb04fa5e 100644
--- a/sysdeps/unix/sysv/linux/alpha/setrlimit64.c
+++ b/sysdeps/unix/sysv/linux/alpha/setrlimit64.c
@@ -35,11 +35,11 @@ __old_setrlimit64 (enum __rlimit_resource resource,
 {
   struct rlimit64 krlimits;
 
-  if (rlimits->rlim_cur == OLD_RLIM64_INFINITY)
+  if (rlimits->rlim_cur >= OLD_RLIM64_INFINITY)
     krlimits.rlim_cur = RLIM64_INFINITY;
   else
     krlimits.rlim_cur = rlimits->rlim_cur;
-  if (rlimits->rlim_max == OLD_RLIM64_INFINITY)
+  if (rlimits->rlim_max >= OLD_RLIM64_INFINITY)
     krlimits.rlim_max = RLIM64_INFINITY;
   else
     krlimits.rlim_max = rlimits->rlim_max;