mem: fix crash on hugepage mapping error

In ASLR-enabled system, it is possible that selected
virtual space is occupied by program segments. Therefore,
error path should not blindly unmap all memmory segments
but only those already mapped.

Steps that lead to crash:
1. memeseg 0 in secondary process overlaps with libc.so
2. mmap of /dev/zero fails for virtual space of memseg 0
3. munmap of memseg 0 leads to unmapping libc.so itself
4. app gets SIGSEGV after returning from syscall to libc

Fixes: ea329d7f8e34 ("mem: fix leak after mapping failure")

Signed-off-by: Maciej Czekaj <maciej.czekaj@caviumnetworks.com>

diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c b/lib/librte_eal/linuxapp/eal/eal_memory.c
index 8add643..b0049e2 100644 (file)
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -1278,6 +1278,7 @@ rte_eal_hugepage_attach(void)
        struct hugepage_file *hp = NULL;
        unsigned num_hp = 0;
        unsigned i, s = 0; /* s used to track the segment number */
+       unsigned max_seg = RTE_MAX_MEMSEG;
        off_t size;
        int fd, fd_zero = -1, fd_hugepage = -1;
 
@@ -1336,6 +1337,9 @@ rte_eal_hugepage_attach(void)
                                "in /dev/zero to requested address [%p]: '%s'\n",
                                (unsigned long long)mcfg->memseg[s].len,
                                mcfg->memseg[s].addr, strerror(errno));
+                       max_seg = s;
+                       if (base_addr != MAP_FAILED)
+                               munmap(base_addr, mcfg->memseg[s].len);
                        if (aslr_enabled() > 0) {
                                RTE_LOG(ERR, EAL, "It is recommended to "
                                        "disable ASLR in the kernel "
@@ -1404,11 +1408,8 @@ rte_eal_hugepage_attach(void)
        return 0;
 
 error:
-       s = 0;
-       while (s < RTE_MAX_MEMSEG && mcfg->memseg[s].len > 0) {
-               munmap(mcfg->memseg[s].addr, mcfg->memseg[s].len);
-               s++;
-       }
+       for (i = 0; i < max_seg && mcfg->memseg[i].len > 0; i++)
+               munmap(mcfg->memseg[i].addr, mcfg->memseg[i].len);
        if (hp != NULL && hp != MAP_FAILED)
                munmap(hp, size);
        if (fd_zero >= 0)