>From b5d429f7cd357a8cf8e49480d58b083892e209f0 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Sat, 24 May 2014 00:14:27 +0200 Subject: [PATCH] workaround for broken kernel side RLIM_INFINITY handling on mips On 32 bit mips the kernel uses -1UL/2 to mark RLIM_INFINITY (and this is the definition in the userspace api), but since it is in the middle of the valid range of limits and limits are often compared with relational operators, various kernel side logic is broken if larger than -1UL/2 limits are used. So we truncate the limits to -1UL/2 in get/setrlimit and prlimit. Even if the kernel side logic consistently treated -1UL/2 as greater than any other limit value, there wouldn't be any clean workaround that allowed using large limits: * using -1UL/2 as RLIM_INFINITY in userspace would mean different infinity value for get/setrlimt and prlimit (where infinity is always -1ULL) and userspace logic could break easily (just like the kernel is broken now) and more special case code would be needed for mips. * translating -1UL/2 kernel side value to -1ULL in userspace would mean that -1UL/2 limit cannot be set (eg. -1UL/2+1 had to be passed to the kernel instead). --- arch/mips/bits/resource.h | 2 ++ src/linux/prlimit.c | 20 ++++++++++++++++++++ src/misc/getrlimit.c | 10 ++++++++++ src/misc/setrlimit.c | 6 ++++++ 4 files changed, 38 insertions(+) diff --git a/arch/mips/bits/resource.h b/arch/mips/bits/resource.h index 414a405..4d8e43b 100644 --- a/arch/mips/bits/resource.h +++ b/arch/mips/bits/resource.h @@ -1,3 +1,5 @@ +#define __broken_RLIM_INFINITY + #define RLIMIT_NOFILE 5 #define RLIMIT_AS 6 #define RLIMIT_RSS 7 diff --git a/src/linux/prlimit.c b/src/linux/prlimit.c index d1639cc..12a9ba9 100644 --- a/src/linux/prlimit.c +++ b/src/linux/prlimit.c @@ -3,10 +3,30 @@ #include "syscall.h" #include "libc.h" +#ifdef __broken_RLIM_INFINITY +#define FIX(x) ((x) >= -1UL/2 ? RLIM_INFINITY : (x)) +int prlimit(pid_t pid, int resource, const struct rlimit *new_limit, struct rlimit *old_limit) +{ + struct rlimit tmp; + int r; + if (new_limit) { + tmp.rlim_cur = FIX(new_limit->rlim_cur); + tmp.rlim_max = FIX(new_limit->rlim_max); + new_limit = &tmp; + } + r = syscall(SYS_prlimit64, pid, resource, new_limit, old_limit); + if (old_limit) { + old_limit->rlim_cur = FIX(old_limit->rlim_cur); + old_limit->rlim_max = FIX(old_limit->rlim_max); + } + return r; +} +#else int prlimit(pid_t pid, int resource, const struct rlimit *new_limit, struct rlimit *old_limit) { return syscall(SYS_prlimit64, pid, resource, new_limit, old_limit); } +#endif #undef prlimit64 LFS64(prlimit); diff --git a/src/misc/getrlimit.c b/src/misc/getrlimit.c index b7bbd06..a6097cf 100644 --- a/src/misc/getrlimit.c +++ b/src/misc/getrlimit.c @@ -3,14 +3,24 @@ #include "syscall.h" #include "libc.h" +#ifdef __broken_RLIM_INFINITY +#define FIX(x) ((x) >= -1UL/2 ? RLIM_INFINITY : (x)) +#else +#define FIX(x) (x) +#endif + int getrlimit(int resource, struct rlimit *rlim) { unsigned long k_rlim[2]; int ret = syscall(SYS_prlimit64, 0, resource, 0, rlim); + rlim->rlim_cur = FIX(rlim->rlim_cur); + rlim->rlim_max = FIX(rlim->rlim_max); if (!ret || errno != ENOSYS) return ret; if (syscall(SYS_getrlimit, resource, k_rlim) < 0) return -1; + k_rlim[0] = FIX(k_rlim[0]); + k_rlim[1] = FIX(k_rlim[1]); rlim->rlim_cur = k_rlim[0] == -1UL ? RLIM_INFINITY : k_rlim[0]; rlim->rlim_max = k_rlim[1] == -1UL ? RLIM_INFINITY : k_rlim[1]; return 0; diff --git a/src/misc/setrlimit.c b/src/misc/setrlimit.c index ddc13e9..665b67d 100644 --- a/src/misc/setrlimit.c +++ b/src/misc/setrlimit.c @@ -8,6 +8,12 @@ int __setrlimit(int resource, const struct rlimit *rlim) { unsigned long k_rlim[2]; +#ifdef __broken_RLIM_INFINITY + struct rlimit tmp; + tmp.rlim_cur = MIN(rlim->rlim_cur, -1UL/2); + tmp.rlim_max = MIN(rlim->rlim_max, -1UL/2); + rlim = &tmp; +#endif int ret = __syscall(SYS_prlimit64, 0, resource, rlim, 0); if (ret != -ENOSYS) return ret; k_rlim[0] = MIN(rlim->rlim_cur, -1UL); -- 1.7.10.4