| Message ID | 6dac22b2a8a22254fc538054cb42a32e53d2482b.1629355682.git.xuyu@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm/swap: consider max pages in iomap_swapfile_add_extent | expand |
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
On Thu, Aug 19, 2021 at 02:52:05PM +0800, Xu Yu wrote: > When the max pages (last_page in the swap header + 1) is smaller than > the total pages (inode size) of the swapfile, iomap_swapfile_activate > overwrites sis->max with total pages. > > However, frontswap_map is allocated using max pages. When test and clear > the sis offset, which is larger than max pages, of frontswap_map in > __frontswap_invalidate_page(), neighbors of frontswap_map may be > overwritten, i.e., slab is polluted. > > This fixes the issue by considering the limitation of max pages of swap > info in iomap_swapfile_add_extent(). > > To reproduce the case, compile kernel with slub RED ZONE, then run test: > $ sudo stress-ng -a 1 -x softlockup,resources -t 1h --metrics --times \ > --verify -v -Y /root/tmpdir/stress-ng/stress-statistic-12.yaml \ > --log-file /root/tmpdir/stress-ng/stress-logfile-12.txt \ > --temp-path /root/tmpdir/stress-ng/ > > We'll get the following error log usually within 5 minutes. > > [ 1151.015141] ============================================================================= > [ 1151.016489] BUG kmalloc-16 (Not tainted): Right Redzone overwritten > [ 1151.017486] ----------------------------------------------------------------------------- > [ 1151.017486] > [ 1151.018997] Disabling lock debugging due to kernel taint > [ 1151.019873] INFO: 0x0000000084e43932-0x0000000098d17cae @offset=7392. First byte 0x0 instead of 0xcc > [ 1151.021303] INFO: Allocated in __do_sys_swapon+0xcf6/0x1170 age=43417 cpu=9 pid=3816 > [ 1151.022538] __slab_alloc+0xe/0x20 > [ 1151.023069] __kmalloc_node+0xfd/0x4b0 > [ 1151.023704] __do_sys_swapon+0xcf6/0x1170 > [ 1151.024346] do_syscall_64+0x33/0x40 > [ 1151.024925] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 1151.025749] INFO: Freed in put_cred_rcu+0xa1/0xc0 age=43424 cpu=3 pid=2041 > [ 1151.026889] kfree+0x276/0x2b0 > [ 1151.027405] put_cred_rcu+0xa1/0xc0 > [ 1151.027949] rcu_do_batch+0x17d/0x410 > [ 1151.028566] rcu_core+0x14e/0x2b0 > [ 1151.029084] __do_softirq+0x101/0x29e > [ 1151.029645] asm_call_irq_on_stack+0x12/0x20 > [ 1151.030381] do_softirq_own_stack+0x37/0x40 > [ 1151.031037] do_softirq.part.15+0x2b/0x30 > [ 1151.031710] __local_bh_enable_ip+0x4b/0x50 > [ 1151.032412] copy_fpstate_to_sigframe+0x111/0x360 > [ 1151.033197] __setup_rt_frame+0xce/0x480 > [ 1151.033809] arch_do_signal+0x1a3/0x250 > [ 1151.034463] exit_to_user_mode_prepare+0xcf/0x110 > [ 1151.035242] syscall_exit_to_user_mode+0x27/0x190 > [ 1151.035970] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 1151.036795] INFO: Slab 0x000000003b9de4dc objects=44 used=9 fp=0x00000000539e349e flags=0xfffffc0010201 > [ 1151.038323] INFO: Object 0x000000004855ba01 @offset=7376 fp=0x0000000000000000 > [ 1151.038323] > [ 1151.039683] Redzone 000000008d0afd3d: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc ................ > [ 1151.041180] Object 000000004855ba01: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > [ 1151.042714] Redzone 0000000084e43932: 00 00 00 c0 cc cc cc cc ........ > [ 1151.044120] Padding 000000000864c042: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ > [ 1151.045615] CPU: 5 PID: 3816 Comm: stress-ng Tainted: G B 5.10.50+ #7 > [ 1151.046846] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 > [ 1151.048633] Call Trace: > [ 1151.049072] dump_stack+0x57/0x6a > [ 1151.049585] check_bytes_and_report+0xed/0x110 > [ 1151.050320] check_object+0x1eb/0x290 > [ 1151.050924] ? __x64_sys_swapoff+0x39a/0x540 > [ 1151.051646] free_debug_processing+0x151/0x350 > [ 1151.052333] __slab_free+0x21a/0x3a0 > [ 1151.052938] ? _cond_resched+0x2d/0x40 > [ 1151.053529] ? __vunmap+0x1de/0x220 > [ 1151.054139] ? __x64_sys_swapoff+0x39a/0x540 > [ 1151.054796] ? kfree+0x276/0x2b0 > [ 1151.055307] kfree+0x276/0x2b0 > [ 1151.055832] __x64_sys_swapoff+0x39a/0x540 > [ 1151.056466] do_syscall_64+0x33/0x40 > [ 1151.057084] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 1151.057866] RIP: 0033:0x150340b0ffb7 > [ 1151.058481] Code: Unable to access opcode bytes at RIP 0x150340b0ff8d. > [ 1151.059537] RSP: 002b:00007fff7f4ee238 EFLAGS: 00000246 ORIG_RAX: 00000000000000a8 > [ 1151.060768] RAX: ffffffffffffffda RBX: 00007fff7f4ee66c RCX: 0000150340b0ffb7 > [ 1151.061904] RDX: 000000000000000a RSI: 0000000000018094 RDI: 00007fff7f4ee860 > [ 1151.063033] RBP: 00007fff7f4ef980 R08: 0000000000000000 R09: 0000150340a672bd > [ 1151.064135] R10: 00007fff7f4edca0 R11: 0000000000000246 R12: 0000000000018094 > [ 1151.065253] R13: 0000000000000005 R14: 000000000160d930 R15: 00007fff7f4ee66c > [ 1151.066413] FIX kmalloc-16: Restoring 0x0000000084e43932-0x0000000098d17cae=0xcc > [ 1151.066413] > [ 1151.067890] FIX kmalloc-16: Object at 0x000000004855ba01 not freed > > Fixes: 0e6895ba00b7 ("ext4: implement swap_activate aops using iomap") > Signed-off-by: Gang Deng <gavin.dg@linux.alibaba.com> > Signed-off-by: Xu Yu <xuyu@linux.alibaba.com> > Reviewed-by: Darrick J. Wong <djwong@kernel.org> Applied, thanks. I've reworked the second paragraph slightly: "However, frontswap_map is a swap page state bitmap allocated using the initial sis->max page count read from the swap header. If swapfile activation increases sis->max, it's possible for the frontswap code to walk off the end of the bitmap, thereby corrupting kernel memory." --D > --- > v1->v2: > - update the commit log > - add Reviewed-by of Darrick J. Wong > --- > fs/iomap/swapfile.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/iomap/swapfile.c b/fs/iomap/swapfile.c > index a5e478de1417..2ceea45aefd8 100644 > --- a/fs/iomap/swapfile.c > +++ b/fs/iomap/swapfile.c > @@ -30,11 +30,16 @@ static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi) > { > struct iomap *iomap = &isi->iomap; > unsigned long nr_pages; > + unsigned long max_pages; > uint64_t first_ppage; > uint64_t first_ppage_reported; > uint64_t next_ppage; > int error; > > + if (unlikely(isi->nr_pages >= isi->sis->max)) > + return 0; > + max_pages = isi->sis->max - isi->nr_pages; > + > /* > * Round the start up and the end down so that the physical > * extent aligns to a page boundary. > @@ -47,6 +52,7 @@ static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi) > if (first_ppage >= next_ppage) > return 0; > nr_pages = next_ppage - first_ppage; > + nr_pages = min(nr_pages, max_pages); > > /* > * Calculate how much swap space we're adding; the first page contains > -- > 2.20.1.2432.ga663e714 >
diff --git a/fs/iomap/swapfile.c b/fs/iomap/swapfile.c index a5e478de1417..2ceea45aefd8 100644 --- a/fs/iomap/swapfile.c +++ b/fs/iomap/swapfile.c @@ -30,11 +30,16 @@ static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi) { struct iomap *iomap = &isi->iomap; unsigned long nr_pages; + unsigned long max_pages; uint64_t first_ppage; uint64_t first_ppage_reported; uint64_t next_ppage; int error; + if (unlikely(isi->nr_pages >= isi->sis->max)) + return 0; + max_pages = isi->sis->max - isi->nr_pages; + /* * Round the start up and the end down so that the physical * extent aligns to a page boundary. @@ -47,6 +52,7 @@ static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi) if (first_ppage >= next_ppage) return 0; nr_pages = next_ppage - first_ppage; + nr_pages = min(nr_pages, max_pages); /* * Calculate how much swap space we're adding; the first page contains
When the max pages (last_page in the swap header + 1) is smaller than the total pages (inode size) of the swapfile, iomap_swapfile_activate overwrites sis->max with total pages. However, frontswap_map is allocated using max pages. When test and clear the sis offset, which is larger than max pages, of frontswap_map in __frontswap_invalidate_page(), neighbors of frontswap_map may be overwritten, i.e., slab is polluted. This fixes the issue by considering the limitation of max pages of swap info in iomap_swapfile_add_extent(). To reproduce the case, compile kernel with slub RED ZONE, then run test: $ sudo stress-ng -a 1 -x softlockup,resources -t 1h --metrics --times \ --verify -v -Y /root/tmpdir/stress-ng/stress-statistic-12.yaml \ --log-file /root/tmpdir/stress-ng/stress-logfile-12.txt \ --temp-path /root/tmpdir/stress-ng/ We'll get the following error log usually within 5 minutes. [ 1151.015141] ============================================================================= [ 1151.016489] BUG kmalloc-16 (Not tainted): Right Redzone overwritten [ 1151.017486] ----------------------------------------------------------------------------- [ 1151.017486] [ 1151.018997] Disabling lock debugging due to kernel taint [ 1151.019873] INFO: 0x0000000084e43932-0x0000000098d17cae @offset=7392. First byte 0x0 instead of 0xcc [ 1151.021303] INFO: Allocated in __do_sys_swapon+0xcf6/0x1170 age=43417 cpu=9 pid=3816 [ 1151.022538] __slab_alloc+0xe/0x20 [ 1151.023069] __kmalloc_node+0xfd/0x4b0 [ 1151.023704] __do_sys_swapon+0xcf6/0x1170 [ 1151.024346] do_syscall_64+0x33/0x40 [ 1151.024925] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 1151.025749] INFO: Freed in put_cred_rcu+0xa1/0xc0 age=43424 cpu=3 pid=2041 [ 1151.026889] kfree+0x276/0x2b0 [ 1151.027405] put_cred_rcu+0xa1/0xc0 [ 1151.027949] rcu_do_batch+0x17d/0x410 [ 1151.028566] rcu_core+0x14e/0x2b0 [ 1151.029084] __do_softirq+0x101/0x29e [ 1151.029645] asm_call_irq_on_stack+0x12/0x20 [ 1151.030381] do_softirq_own_stack+0x37/0x40 [ 1151.031037] do_softirq.part.15+0x2b/0x30 [ 1151.031710] __local_bh_enable_ip+0x4b/0x50 [ 1151.032412] copy_fpstate_to_sigframe+0x111/0x360 [ 1151.033197] __setup_rt_frame+0xce/0x480 [ 1151.033809] arch_do_signal+0x1a3/0x250 [ 1151.034463] exit_to_user_mode_prepare+0xcf/0x110 [ 1151.035242] syscall_exit_to_user_mode+0x27/0x190 [ 1151.035970] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 1151.036795] INFO: Slab 0x000000003b9de4dc objects=44 used=9 fp=0x00000000539e349e flags=0xfffffc0010201 [ 1151.038323] INFO: Object 0x000000004855ba01 @offset=7376 fp=0x0000000000000000 [ 1151.038323] [ 1151.039683] Redzone 000000008d0afd3d: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc ................ [ 1151.041180] Object 000000004855ba01: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1151.042714] Redzone 0000000084e43932: 00 00 00 c0 cc cc cc cc ........ [ 1151.044120] Padding 000000000864c042: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ [ 1151.045615] CPU: 5 PID: 3816 Comm: stress-ng Tainted: G B 5.10.50+ #7 [ 1151.046846] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 [ 1151.048633] Call Trace: [ 1151.049072] dump_stack+0x57/0x6a [ 1151.049585] check_bytes_and_report+0xed/0x110 [ 1151.050320] check_object+0x1eb/0x290 [ 1151.050924] ? __x64_sys_swapoff+0x39a/0x540 [ 1151.051646] free_debug_processing+0x151/0x350 [ 1151.052333] __slab_free+0x21a/0x3a0 [ 1151.052938] ? _cond_resched+0x2d/0x40 [ 1151.053529] ? __vunmap+0x1de/0x220 [ 1151.054139] ? __x64_sys_swapoff+0x39a/0x540 [ 1151.054796] ? kfree+0x276/0x2b0 [ 1151.055307] kfree+0x276/0x2b0 [ 1151.055832] __x64_sys_swapoff+0x39a/0x540 [ 1151.056466] do_syscall_64+0x33/0x40 [ 1151.057084] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 1151.057866] RIP: 0033:0x150340b0ffb7 [ 1151.058481] Code: Unable to access opcode bytes at RIP 0x150340b0ff8d. [ 1151.059537] RSP: 002b:00007fff7f4ee238 EFLAGS: 00000246 ORIG_RAX: 00000000000000a8 [ 1151.060768] RAX: ffffffffffffffda RBX: 00007fff7f4ee66c RCX: 0000150340b0ffb7 [ 1151.061904] RDX: 000000000000000a RSI: 0000000000018094 RDI: 00007fff7f4ee860 [ 1151.063033] RBP: 00007fff7f4ef980 R08: 0000000000000000 R09: 0000150340a672bd [ 1151.064135] R10: 00007fff7f4edca0 R11: 0000000000000246 R12: 0000000000018094 [ 1151.065253] R13: 0000000000000005 R14: 000000000160d930 R15: 00007fff7f4ee66c [ 1151.066413] FIX kmalloc-16: Restoring 0x0000000084e43932-0x0000000098d17cae=0xcc [ 1151.066413] [ 1151.067890] FIX kmalloc-16: Object at 0x000000004855ba01 not freed Fixes: 0e6895ba00b7 ("ext4: implement swap_activate aops using iomap") Signed-off-by: Gang Deng <gavin.dg@linux.alibaba.com> Signed-off-by: Xu Yu <xuyu@linux.alibaba.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> --- v1->v2: - update the commit log - add Reviewed-by of Darrick J. Wong --- fs/iomap/swapfile.c | 6 ++++++ 1 file changed, 6 insertions(+)