| Message ID | fbbc0efa2ad81b3dcc00c6dcb15af8189d343af3.1726692825.git.fdmanana@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: send: fix buffer overflow when reversing path that is full | expand |
On Wed, Sep 18, 2024 at 9:57 PM <fdmanana@kernel.org> wrote: > > From: Filipe Manana <fdmanana@suse.com> > > When unreversing a path we are doing a memmove() for a length that > corresponds to the length of the path's content plus 1. This is incorrect > as we shouldn't add the extra 1, that is, the length of our content is > the difference between the path's end offset and the path's start offset, > and there's no NULL termination as we always use the length for all > operations. Most of the time this ends up being harmless because the > path's content is less than the path's buffer length, however when the > content's length matches the size of the buffer, we end up doing a buffer > overflow, which results in a crash like the following on a fortified > kernel: > > Sep 15 23:32:17 sdslinux1 kernel: ------------[ cut here ]------------ > Sep 15 23:32:17 sdslinux1 kernel: strcpy: detected buffer overflow: 20 > byte write of buffer size 19 > Sep 15 23:32:17 sdslinux1 kernel: WARNING: CPU: 3 PID: 3310 at > __fortify_report+0x45/0x50 > Sep 15 23:32:17 sdslinux1 kernel: Modules linked in: nfsd auth_rpcgss > lockd grace nfs_acl bridge stp llc bonding tls vfat fat binfmt_misc > snd_hda_codec_hdmi intel_rapl_msr intel_rapl_common x8 > 6_pkg_temp_thermal intel_powerclamp kvm_intel iTCO_wdt intel_pmc_bxt > spi_intel_platform kvm at24 mei_wdt spi_intel mei_pxp > iTCO_vendor_support mei_hdcp btusb snd_hda_codec_realtek btbcm btinte > l snd_hda_scodec_component i915 rapl iwlwifi snd_hda_codec_generic btrtl > intel_cstate btmtk cec snd_hda_intel intel_uncore cfg80211 > snd_intel_dspcfg drm_buddy coretemp snd_intel_sdw_acpi bluet > ooth ttm pcspkr snd_hda_codec rfkill snd_hda_core snd_hwdep intel_vbtn > snd_pcm mei_me drm_display_helper snd_timer sparse_keymap i2c_i801 mei > snd i2c_smbus lpc_ich soundcore cdc_mbim cdc_wdm cdc_ncm cdc_ether > usbnet crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni > polyval_generic ghash_clmulni_intel sha512_ssse3 sha256_ssse3 sha1_ssse3 > igb r8152 serio_raw i2c_algo_bit mii dca e1000e video wmi sunrpc > Sep 15 23:32:17 sdslinux1 kernel: CPU: 3 UID: 0 PID: 3310 Comm: btrfs > Not tainted 6.11.0-prnet #1 > Sep 15 23:32:17 sdslinux1 kernel: Hardware name: CompuLab Ltd. > sbc-ihsw/Intense-PC2 (IPC2), BIOS IPC2_3.330.7 X64 03/15/2018 > Sep 15 23:32:17 sdslinux1 kernel: RIP: 0010:__fortify_report+0x45/0x50 > Sep 15 23:32:17 sdslinux1 kernel: Code: 48 8b 34 (...) > Sep 15 23:32:17 sdslinux1 kernel: RSP: 0018:ffff97ebc0d6f650 EFLAGS: > 00010246 > Sep 15 23:32:17 sdslinux1 kernel: RAX: 7749924ef60fa600 RBX: > ffff8bf5446a521a RCX: 0000000000000027 > Sep 15 23:32:17 sdslinux1 kernel: RDX: 00000000ffffdfff RSI: > ffff97ebc0d6f548 RDI: ffff8bf84e7a1cc8 > Sep 15 23:32:17 sdslinux1 kernel: RBP: ffff8bf548574080 R08: > ffffffffa8c40e10 R09: 0000000000005ffd > Sep 15 23:32:17 sdslinux1 kernel: R10: 0000000000000004 R11: > ffffffffa8c70e10 R12: ffff8bf551eef400 > Sep 15 23:32:17 sdslinux1 kernel: R13: 0000000000000000 R14: > 0000000000000013 R15: 00000000000003a8 > Sep 15 23:32:17 sdslinux1 kernel: FS: 00007fae144de8c0(0000) > GS:ffff8bf84e780000(0000) knlGS:0000000000000000 > Sep 15 23:32:17 sdslinux1 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: > 0000000080050033 > Sep 15 23:32:17 sdslinux1 kernel: CR2: 00007fae14691690 CR3: > 00000001027a2003 CR4: 00000000001706f0 > Sep 15 23:32:17 sdslinux1 kernel: Call Trace: > Sep 15 23:32:17 sdslinux1 kernel: <TASK> > Sep 15 23:32:17 sdslinux1 kernel: ? __warn+0x12a/0x1d0 > Sep 15 23:32:17 sdslinux1 kernel: ? __fortify_report+0x45/0x50 > Sep 15 23:32:17 sdslinux1 kernel: ? report_bug+0x154/0x1c0 > Sep 15 23:32:17 sdslinux1 kernel: ? handle_bug+0x42/0x70 > Sep 15 23:32:17 sdslinux1 kernel: ? exc_invalid_op+0x1a/0x50 > Sep 15 23:32:17 sdslinux1 kernel: ? asm_exc_invalid_op+0x1a/0x20 > Sep 15 23:32:17 sdslinux1 kernel: ? __fortify_report+0x45/0x50 > Sep 15 23:32:17 sdslinux1 kernel: __fortify_panic+0x9/0x10 > Sep 15 23:32:17 sdslinux1 kernel: __get_cur_name_and_parent+0x3bc/0x3c0 > Sep 15 23:32:17 sdslinux1 kernel: get_cur_path+0x207/0x3b0 > Sep 15 23:32:17 sdslinux1 kernel: send_extent_data+0x709/0x10d0 > Sep 15 23:32:17 sdslinux1 kernel: ? find_parent_nodes+0x22df/0x25d0 > Sep 15 23:32:17 sdslinux1 kernel: ? mas_nomem+0x13/0x90 > Sep 15 23:32:17 sdslinux1 kernel: ? mtree_insert_range+0xa5/0x110 > Sep 15 23:32:17 sdslinux1 kernel: ? btrfs_lru_cache_store+0x5f/0x1e0 > Sep 15 23:32:17 sdslinux1 kernel: ? iterate_extent_inodes+0x52d/0x5a0 > Sep 15 23:32:17 sdslinux1 kernel: process_extent+0xa96/0x11a0 > Sep 15 23:32:17 sdslinux1 kernel: ? __pfx_lookup_backref_cache+0x10/0x10 > Sep 15 23:32:17 sdslinux1 kernel: ? __pfx_store_backref_cache+0x10/0x10 > Sep 15 23:32:17 sdslinux1 kernel: ? __pfx_iterate_backrefs+0x10/0x10 > Sep 15 23:32:17 sdslinux1 kernel: ? __pfx_check_extent_item+0x10/0x10 > Sep 15 23:32:17 sdslinux1 kernel: changed_cb+0x6fa/0x930 > Sep 15 23:32:17 sdslinux1 kernel: ? tree_advance+0x362/0x390 > Sep 15 23:32:17 sdslinux1 kernel: ? memcmp_extent_buffer+0xd7/0x160 > Sep 15 23:32:17 sdslinux1 kernel: send_subvol+0xf0a/0x1520 > Sep 15 23:32:17 sdslinux1 kernel: btrfs_ioctl_send+0x106b/0x11d0 > Sep 15 23:32:17 sdslinux1 kernel: ? __pfx___clone_root_cmp_sort+0x10/0x10 > Sep 15 23:32:17 sdslinux1 kernel: _btrfs_ioctl_send+0x1ac/0x240 > Sep 15 23:32:17 sdslinux1 kernel: btrfs_ioctl+0x75b/0x850 > Sep 15 23:32:17 sdslinux1 kernel: __se_sys_ioctl+0xca/0x150 > Sep 15 23:32:17 sdslinux1 kernel: do_syscall_64+0x85/0x160 > Sep 15 23:32:17 sdslinux1 kernel: ? __count_memcg_events+0x69/0x100 > Sep 15 23:32:17 sdslinux1 kernel: ? handle_mm_fault+0x1327/0x15c0 > Sep 15 23:32:17 sdslinux1 kernel: ? __se_sys_rt_sigprocmask+0xf1/0x180 > Sep 15 23:32:17 sdslinux1 kernel: ? syscall_exit_to_user_mode+0x75/0xa0 > Sep 15 23:32:17 sdslinux1 kernel: ? do_syscall_64+0x91/0x160 > Sep 15 23:32:17 sdslinux1 kernel: ? do_user_addr_fault+0x21d/0x630 > Sep 15 23:32:17 sdslinux1 kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e > Sep 15 23:32:17 sdslinux1 kernel: RIP: 0033:0x7fae145eeb4f > Sep 15 23:32:17 sdslinux1 kernel: Code: 00 48 89 (...) > Sep 15 23:32:17 sdslinux1 kernel: RSP: 002b:00007ffdf1cb09b0 EFLAGS: > 00000246 ORIG_RAX: 0000000000000010 > Sep 15 23:32:17 sdslinux1 kernel: RAX: ffffffffffffffda RBX: > 0000000000000004 RCX: 00007fae145eeb4f > Sep 15 23:32:17 sdslinux1 kernel: RDX: 00007ffdf1cb0ad0 RSI: > 0000000040489426 RDI: 0000000000000004 > Sep 15 23:32:17 sdslinux1 kernel: RBP: 00000000000078fe R08: > 00007fae144006c0 R09: 00007ffdf1cb0927 > Sep 15 23:32:17 sdslinux1 kernel: R10: 0000000000000008 R11: > 0000000000000246 R12: 00007ffdf1cb1ce8 > Sep 15 23:32:17 sdslinux1 kernel: R13: 0000000000000003 R14: > 000055c499fab2e0 R15: 0000000000000004 > Sep 15 23:32:17 sdslinux1 kernel: </TASK> > Sep 15 23:32:17 sdslinux1 kernel: ---[ end trace 0000000000000000 ]--- > Sep 15 23:32:17 sdslinux1 kernel: ------------[ cut here ]------------ > > Fix this passing the actual length to memmove(), not summing 1. > > Reported-by: David Arendt <admin@prnet.org> > Link: https://lore.kernel.org/linux-btrfs/cee4591a-3088-49ba-99b8-d86b4242b8bd@prnet.org/ > Fixes: 31db9f7c23fb ("Btrfs: introduce BTRFS_IOC_SEND for btrfs send/receive") > Signed-off-by: Filipe Manana <fdmanana@suse.com> > --- > fs/btrfs/send.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c > index 7f48ba6c1c77..0c5a62da802d 100644 > --- a/fs/btrfs/send.c > +++ b/fs/btrfs/send.c > @@ -620,7 +620,7 @@ static void fs_path_unreverse(struct fs_path *p) > len = p->end - p->start; > p->start = p->buf; > p->end = p->start + len; > - memmove(p->start, tmp, len + 1); > + memmove(p->start, tmp, len); Scratch this, the problem is elsewhere, reversed paths always end with a nul terminator. > p->reversed = 0; > } > > -- > 2.43.0 > >
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 7f48ba6c1c77..0c5a62da802d 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -620,7 +620,7 @@ static void fs_path_unreverse(struct fs_path *p) len = p->end - p->start; p->start = p->buf; p->end = p->start + len; - memmove(p->start, tmp, len + 1); + memmove(p->start, tmp, len); p->reversed = 0; }