CVE-2024-26688 Information
Description
In the Linux kernel the following vulnerability has been resolved:
fshugetlb: fix NULL pointer dereference in hugetlbs_fill_super
When configuring a hugetlb filesystem via the fsconfig() syscall there is a possible NULL dereference in hugetlbfs_fill_super() caused by assigning NULL to ctx->hstate in hugetlbfs_parse_param() when the requested pagesize is non valid.
E.g: Taking the following steps:
fd = fsopen(\hugetlbfs\ FSOPEN_CLOEXEC);
fsconfig(fd FSCONFIG_SET_STRING \pagesize\ \1024\ 0);
fsconfig(fd FSCONFIG_CMD_CREATE NULL NULL 0);
Given that the requested \pagesize\ is invalid ctxt->hstate will be replaced with NULL losing its previous value and we will print an error:
… … case Opt_pagesize: ps = memparse(param->string &rest); ctx->hstate = h; if (!ctx->hstate) pr_err(�nsupported page size %lu MB\n\ ps / SZ_1M); return -EINVAL;
return 0; … …
This is a problem because later on we will dereference ctxt->hstate in hugetlbfs_fill_super()
… … sb->s_blocksize = huge_page_size(ctx->hstate); … …
Causing below Oops.
Fix this by replacing cxt->hstate value only when then pagesize is known to be valid.
kernel: hugetlbfs: Unsupported page size 0 MB
kernel: BUG: kernel NULL pointer dereference address: 0000000000000028
kernel: PF: supervisor read access in kernel mode
kernel: PF: error_code(0x0000) - not-present page
kernel: PGD 800000010f66c067 P4D 800000010f66c067 PUD 1b22f8067 PMD 0
kernel: Oops: 0000 [1] PREEMPT SMP PTI
kernel: CPU: 4 PID: 5659 Comm: syscall Tainted: G E 6.8.0-rc2-default+ 22 5a47c3fef76212addcc6eb71344aabc35190ae8f
kernel: Hardware name: Intel Corp. GROVEPORT/GROVEPORT BIOS GVPRCRB1.86B.0016.D04.1705030402 05/03/2017
kernel: RIP: 0010:hugetlbfs_fill_super+0xb4/0x1a0
kernel: Code: 48 8b 3b e8 3e c6 ed ff 48 85 c0 48 89 45 20 0f 84 d6 00 00 00 48 b8 ff ff ff ff ff ff ff 7f 4c 89 e7 49 89 44 24 20 48 8b 03 <8b> 48 28 b8 00 10 00 00 48 d3 e0 49 89 44 24 18 48 8b 03 8b 40 28
kernel: RSP: 0018:ffffbe9960fcbd48 EFLAGS: 00010246
kernel: RAX: 0000000000000000 RBX: ffff9af5272ae780 RCX: 0000000000372004
kernel: RDX: ffffffffffffffff RSI: ffffffffffffffff RDI: ffff9af555e9b000
kernel: RBP: ffff9af52ee66b00 R08: 0000000000000040 R09: 0000000000370004
kernel: R10: ffffbe9960fcbd48 R11: 0000000000000040 R12: ffff9af555e9b000
kernel: R13: ffffffffa66b86c0 R14: ffff9af507d2f400 R15: ffff9af507d2f400
kernel: FS: 00007ffbc0ba4740(0000) GS:ffff9b0bd7000000(0000) knlGS:0000000000000000
kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kernel: CR2: 0000000000000028 CR3: 00000001b1ee0000 CR4: 00000000001506f0
kernel: Call Trace:
kernel:
kernel: ? __die_body+0x1a/0x60
kernel: ? page_fault_oops+0x16f/0x4a0
kernel: ? search_bpf_extables+0x65/0x70
kernel: ? fixup_exception+0x22/0x310
kernel: ? exc_page_fault+0x69/0x150
kernel: ? asm_exc_page_fault+0x22/0x30
kernel: ? __pfx_hugetlbfs_fill_super+0x10/0x10
kernel: ? hugetlbfs_fill_super+0xb4/0x1a0
kernel: ? hugetlbfs_fill_super+0x28/0x1a0
kernel: ? __pfx_hugetlbfs_fill_super+0x10/0x10
kernel: vfs_get_super+0x40/0xa0
kernel: ? __pfx_bpf_lsm_capable+0x10/0x10
kernel: vfs_get_tree+0x25/0xd0
kernel: vfs_cmd_create+0x64/0xe0
kernel: __x64_sys_fsconfig+0x395/0x410
kernel: do_syscall_64+0x80/0x160
kernel: ? syscall_exit_to_user_mode+0x82/0x240
kernel: ? do_syscall_64+0x8d/0x160
kernel: ? syscall_exit_to_user_mode+0x82/0x240
kernel: ? do_syscall_64+0x8d/0x160
kernel: ? exc_page_fault+0x69/0x150
kernel: entry_SYSCALL_64_after_hwframe+0x6e/0x76
kernel: RIP: 0033:0x7ffbc0cb87c9
kernel: Code: 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 97 96 0d 00 f7 d8 64 89 01 48
kernel: RSP: 002b:00007ffc29d2f388 EFLAGS: 00000206 ORIG_RAX: 00000000000001af
kernel: RAX: fffffffffff
truncated—
Reference
https://git.kernel.org/stable/c/1dde8ef4b7a749ae1bc73617c91775631d167557 https://git.kernel.org/stable/c/80d852299987a8037be145a94f41874228f1a773 https://git.kernel.org/stable/c/22850c9950a4e43a67299755d11498f3292d02ff https://git.kernel.org/stable/c/2e2c07104b4904aed1389a59b25799b95a85b5b9 https://git.kernel.org/stable/c/13c5a9fb07105557a1fa9efdb4f23d7ef30b7274 https://git.kernel.org/stable/c/ec78418801ef7b0c22cd6a30145ec480dd48db39 https://git.kernel.org/stable/c/79d72c68c58784a3e1cd2378669d51bfd0cb7498
Share on: