* Re: [PATCH] lz4: fixs use-after-free Read in LZ4_decompress_safe_partial [not found] <20210630032358.949122-1-cy.fan@huawei.com> @ 2021-06-30 11:42 ` Gao Xiang 2021-06-30 17:49 ` Nick Terrell via Linux-erofs 2021-07-01 2:32 ` Chengyang Fan 0 siblings, 2 replies; 4+ messages in thread From: Gao Xiang @ 2021-06-30 11:42 UTC (permalink / raw) To: Chengyang Fan Cc: sfr, linux-kernel, terrelln, Yann Collet, akpm, linux-erofs, thisisrast7 (also +cc Yann as well as Nick..) Hi Chengyang, If I understand correctly, is this a manually produced fuzzed EROFS compressed data? If it's just a normal image, could you also share the original image? On Wed, Jun 30, 2021 at 11:23:58AM +0800, Chengyang Fan wrote: > ================================================================== > BUG: KASAN: use-after-free in get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] > BUG: KASAN: use-after-free in LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] > BUG: KASAN: use-after-free in LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] > BUG: KASAN: use-after-free in LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 > Read of size 2 at addr ffff888017851000 by task kworker/u12:0/2056 > > CPU: 0 PID: 2056 Comm: kworker/u12:0 Not tainted 5.10.40 #2 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 > Workqueue: erofs_unzipd z_erofs_decompressqueue_work > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x137/0x1be lib/dump_stack.c:118 > print_address_description+0x6c/0x640 mm/kasan/report.c:385 > __kasan_report mm/kasan/report.c:545 [inline] > kasan_report+0x13d/0x1e0 mm/kasan/report.c:562 > get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] > LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] > LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] > LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 > z_erofs_lz4_decompress+0x839/0xc90 fs/erofs/decompressor.c:162 > z_erofs_decompress_generic fs/erofs/decompressor.c:291 [inline] > z_erofs_decompress+0x57e/0xe10 fs/erofs/decompressor.c:344 > z_erofs_decompress_pcluster+0x13d1/0x2310 fs/erofs/zdata.c:880 > z_erofs_decompress_queue fs/erofs/zdata.c:958 [inline] > z_erofs_decompressqueue_work+0xde/0x140 fs/erofs/zdata.c:969 > process_one_work+0x780/0xfc0 kernel/workqueue.c:2269 > worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415 > kthread+0x39a/0x3c0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 > > The buggy address belongs to the page: > page:00000000a79b76f1 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17851 > flags: 0xfff00000000000() > raw: 00fff00000000000 ffffea000081b9c8 ffffea00006ac6c8 0000000000000000 > raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff888017850f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff888017850f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff888017851000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ^ > ffff888017851080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff888017851100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ================================================================== > erofs: (device loop0): z_erofs_lz4_decompress: failed to decompress -4099 in[4096, 0] out[9000] > > Off-by-one error causes the above issue. In LZ4_decompress_generic(), > `iend = src + srcSize`. It means the valid address range should be > [src, iend - 1]. Therefore, when checking whether the reading is > out-of-bounds, it should be `>= iend` rather than `> iend`. > > Reported-by: Hulk Robot <hulkci@huawei.com> > Signed-off-by: Chengyang Fan <cy.fan@huawei.com> > --- > lib/lz4/lz4_decompress.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c > index 926f4823d5ea..ec51837cd31f 100644 > --- a/lib/lz4/lz4_decompress.c > +++ b/lib/lz4/lz4_decompress.c > @@ -234,7 +234,7 @@ static FORCE_INLINE int LZ4_decompress_generic( > length = oend - op; > } > if ((endOnInput) > - && (ip + length > iend)) { > + && (ip + length >= iend)) { I'm not sure it should be fixed as this. The current lz4 decompression code was from lz4 1.8.3, and I saw several following up fixes for incomplete input partial decoding in recent LZ4 upstream, you could check them out together. However, EROFS should never pass incomplete lz4 compressed data to the LZ4 side unless it's somewhat a corrupted image on purpose. https://github.com/lz4/lz4/blame/dev/lib/lz4.c Thanks, Gao Xiang > /* > * Error : > * read attempt beyond > -- > 2.18.0.huawei.25 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] lz4: fixs use-after-free Read in LZ4_decompress_safe_partial 2021-06-30 11:42 ` [PATCH] lz4: fixs use-after-free Read in LZ4_decompress_safe_partial Gao Xiang @ 2021-06-30 17:49 ` Nick Terrell via Linux-erofs 2021-07-01 2:34 ` Chengyang Fan 2021-07-01 2:32 ` Chengyang Fan 1 sibling, 1 reply; 4+ messages in thread From: Nick Terrell via Linux-erofs @ 2021-06-30 17:49 UTC (permalink / raw) To: Gao Xiang Cc: Stephen Rothwell, linux-erofs, LKML, Yann Collet, Andrew Morton, Chengyang Fan, Rajat Asthana > On Jun 30, 2021, at 4:42 AM, Gao Xiang <hsiangkao@linux.alibaba.com> wrote: > > (also +cc Yann as well as Nick..) > > Hi Chengyang, > > If I understand correctly, is this a manually produced fuzzed > EROFS compressed data? If it's just a normal image, could you > also share the original image? > > On Wed, Jun 30, 2021 at 11:23:58AM +0800, Chengyang Fan wrote: >> ================================================================== >> BUG: KASAN: use-after-free in get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] >> BUG: KASAN: use-after-free in LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] >> BUG: KASAN: use-after-free in LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] >> BUG: KASAN: use-after-free in LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 >> Read of size 2 at addr ffff888017851000 by task kworker/u12:0/2056 >> >> CPU: 0 PID: 2056 Comm: kworker/u12:0 Not tainted 5.10.40 #2 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 >> Workqueue: erofs_unzipd z_erofs_decompressqueue_work >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x137/0x1be lib/dump_stack.c:118 >> print_address_description+0x6c/0x640 mm/kasan/report.c:385 >> __kasan_report mm/kasan/report.c:545 [inline] >> kasan_report+0x13d/0x1e0 mm/kasan/report.c:562 >> get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] >> LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] >> LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] >> LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 >> z_erofs_lz4_decompress+0x839/0xc90 fs/erofs/decompressor.c:162 >> z_erofs_decompress_generic fs/erofs/decompressor.c:291 [inline] >> z_erofs_decompress+0x57e/0xe10 fs/erofs/decompressor.c:344 >> z_erofs_decompress_pcluster+0x13d1/0x2310 fs/erofs/zdata.c:880 >> z_erofs_decompress_queue fs/erofs/zdata.c:958 [inline] >> z_erofs_decompressqueue_work+0xde/0x140 fs/erofs/zdata.c:969 >> process_one_work+0x780/0xfc0 kernel/workqueue.c:2269 >> worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415 >> kthread+0x39a/0x3c0 kernel/kthread.c:292 >> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 >> >> The buggy address belongs to the page: >> page:00000000a79b76f1 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17851 >> flags: 0xfff00000000000() >> raw: 00fff00000000000 ffffea000081b9c8 ffffea00006ac6c8 0000000000000000 >> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >> page dumped because: kasan: bad access detected >> >> Memory state around the buggy address: >> ffff888017850f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ffff888017850f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >>> ffff888017851000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ^ >> ffff888017851080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ffff888017851100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ================================================================== >> erofs: (device loop0): z_erofs_lz4_decompress: failed to decompress -4099 in[4096, 0] out[9000] >> >> Off-by-one error causes the above issue. In LZ4_decompress_generic(), >> `iend = src + srcSize`. It means the valid address range should be >> [src, iend - 1]. Therefore, when checking whether the reading is >> out-of-bounds, it should be `>= iend` rather than `> iend`. This isn’t correct. The bounds check is correct for the following memcpy(). The problem is the LZ4_readLE16() on line 285 [1]. >> Reported-by: Hulk Robot <hulkci@huawei.com> >> Signed-off-by: Chengyang Fan <cy.fan@huawei.com> >> --- >> lib/lz4/lz4_decompress.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c >> index 926f4823d5ea..ec51837cd31f 100644 >> --- a/lib/lz4/lz4_decompress.c >> +++ b/lib/lz4/lz4_decompress.c >> @@ -234,7 +234,7 @@ static FORCE_INLINE int LZ4_decompress_generic( >> length = oend - op; >> } >> if ((endOnInput) >> - && (ip + length > iend)) { >> + && (ip + length >= iend)) { > > I'm not sure it should be fixed as this. Yeah, this is not the correct fix. `ip + length > iend` is correct for the memcpy(). You would instead need to add another check after the memcpy(). E.g. something like this, taken from upstream [2]. ``` LZ4_memmove(op, ip, length); ip += length; op += length; /* Necessarily EOF, due to parsing restrictions */ - if (!partialDecoding || (cpy == oend)) + if (!partialDecoding || (cpy == oend) || (ip >= (iend-2))) break; ``` This should be enough to fix the out of bounds read you reported. However, I can’t guarantee that this will fix all the issues that have been fixed upstream since v1.8.3. The safest and most robust course of action would be to update the version of LZ4 in the kernel to the latest upstream, which is continuously fuzzed, and doesn't have this issue. Best, Nick Terrell > The current lz4 decompression code was from lz4 1.8.3, and I saw > several following up fixes for incomplete input partial decoding > in recent LZ4 upstream, you could check them out together. However, > EROFS should never pass incomplete lz4 compressed data to the LZ4 > side unless it's somewhat a corrupted image on purpose. > https://github.com/lz4/lz4/blame/dev/lib/lz4.c > > Thanks, > Gao Xiang > >> /* >> * Error : >> * read attempt beyond >> -- >> 2.18.0.huawei.25 [1] https://github.com/torvalds/linux/blob/007b350a58754a93ca9fe50c498cc27780171153/lib/lz4/lz4_decompress.c#L285 [2] https://github.com/lz4/lz4/blob/11efc95c3f02b76ab40e7fbd605677ad6eb141d3/lib/lz4.c#L2059 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] lz4: fixs use-after-free Read in LZ4_decompress_safe_partial 2021-06-30 17:49 ` Nick Terrell via Linux-erofs @ 2021-07-01 2:34 ` Chengyang Fan 0 siblings, 0 replies; 4+ messages in thread From: Chengyang Fan @ 2021-07-01 2:34 UTC (permalink / raw) To: Nick Terrell, Gao Xiang Cc: Stephen Rothwell, LKML, Yann Collet, Andrew Morton, linux-erofs, Rajat Asthana On 2021/7/1 1:49, Nick Terrell wrote: > >> On Jun 30, 2021, at 4:42 AM, Gao Xiang <hsiangkao@linux.alibaba.com> wrote: >> >> (also +cc Yann as well as Nick..) >> >> Hi Chengyang, >> >> If I understand correctly, is this a manually produced fuzzed >> EROFS compressed data? If it's just a normal image, could you >> also share the original image? >> >> On Wed, Jun 30, 2021 at 11:23:58AM +0800, Chengyang Fan wrote: >>> ================================================================== >>> BUG: KASAN: use-after-free in get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] >>> BUG: KASAN: use-after-free in LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] >>> BUG: KASAN: use-after-free in LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] >>> BUG: KASAN: use-after-free in LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 >>> Read of size 2 at addr ffff888017851000 by task kworker/u12:0/2056 >>> >>> CPU: 0 PID: 2056 Comm: kworker/u12:0 Not tainted 5.10.40 #2 >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 >>> Workqueue: erofs_unzipd z_erofs_decompressqueue_work >>> Call Trace: >>> __dump_stack lib/dump_stack.c:77 [inline] >>> dump_stack+0x137/0x1be lib/dump_stack.c:118 >>> print_address_description+0x6c/0x640 mm/kasan/report.c:385 >>> __kasan_report mm/kasan/report.c:545 [inline] >>> kasan_report+0x13d/0x1e0 mm/kasan/report.c:562 >>> get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] >>> LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] >>> LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] >>> LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 >>> z_erofs_lz4_decompress+0x839/0xc90 fs/erofs/decompressor.c:162 >>> z_erofs_decompress_generic fs/erofs/decompressor.c:291 [inline] >>> z_erofs_decompress+0x57e/0xe10 fs/erofs/decompressor.c:344 >>> z_erofs_decompress_pcluster+0x13d1/0x2310 fs/erofs/zdata.c:880 >>> z_erofs_decompress_queue fs/erofs/zdata.c:958 [inline] >>> z_erofs_decompressqueue_work+0xde/0x140 fs/erofs/zdata.c:969 >>> process_one_work+0x780/0xfc0 kernel/workqueue.c:2269 >>> worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415 >>> kthread+0x39a/0x3c0 kernel/kthread.c:292 >>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 >>> >>> The buggy address belongs to the page: >>> page:00000000a79b76f1 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17851 >>> flags: 0xfff00000000000() >>> raw: 00fff00000000000 ffffea000081b9c8 ffffea00006ac6c8 0000000000000000 >>> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >>> page dumped because: kasan: bad access detected >>> >>> Memory state around the buggy address: >>> ffff888017850f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >>> ffff888017850f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >>>> ffff888017851000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>> ^ >>> ffff888017851080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>> ffff888017851100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>> ================================================================== >>> erofs: (device loop0): z_erofs_lz4_decompress: failed to decompress -4099 in[4096, 0] out[9000] >>> >>> Off-by-one error causes the above issue. In LZ4_decompress_generic(), >>> `iend = src + srcSize`. It means the valid address range should be >>> [src, iend - 1]. Therefore, when checking whether the reading is >>> out-of-bounds, it should be `>= iend` rather than `> iend`. > This isn’t correct. The bounds check is correct for the following memcpy(). > The problem is the LZ4_readLE16() on line 285 [1]. Yeah, it's my fault. This fix is incorrect. >>> Reported-by: Hulk Robot <hulkci@huawei.com> >>> Signed-off-by: Chengyang Fan <cy.fan@huawei.com> >>> --- >>> lib/lz4/lz4_decompress.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c >>> index 926f4823d5ea..ec51837cd31f 100644 >>> --- a/lib/lz4/lz4_decompress.c >>> +++ b/lib/lz4/lz4_decompress.c >>> @@ -234,7 +234,7 @@ static FORCE_INLINE int LZ4_decompress_generic( >>> length = oend - op; >>> } >>> if ((endOnInput) >>> - && (ip + length > iend)) { >>> + && (ip + length >= iend)) { >> I'm not sure it should be fixed as this. > Yeah, this is not the correct fix. `ip + length > iend` is correct for the > memcpy(). You would instead need to add another check after the > memcpy(). E.g. something like this, taken from upstream [2]. > > ``` > > LZ4_memmove(op, ip, length); > ip += length; > op += length; > > /* Necessarily EOF, due to parsing restrictions */ > - if (!partialDecoding || (cpy == oend)) > + if (!partialDecoding || (cpy == oend) || (ip >= (iend-2))) > break; > ``` > > This should be enough to fix the out of bounds read you reported. > However, I can’t guarantee that this will fix all the issues that have been > fixed upstream since v1.8.3. > > The safest and most robust course of action would be to update the version > of LZ4 in the kernel to the latest upstream, which is continuously fuzzed, and > doesn't have this issue. > > Best, > Nick Terrell Thanks for pointing this out. I ignored the modifications of LZ4 upstream before. So I'll recheck them and find the right way to fix this error. Thanks, Chengyang Fan >> The current lz4 decompression code was from lz4 1.8.3, and I saw >> several following up fixes for incomplete input partial decoding >> in recent LZ4 upstream, you could check them out together. However, >> EROFS should never pass incomplete lz4 compressed data to the LZ4 >> side unless it's somewhat a corrupted image on purpose. >> https://github.com/lz4/lz4/blame/dev/lib/lz4.c >> >> Thanks, >> Gao Xiang >> >>> /* >>> * Error : >>> * read attempt beyond >>> -- >>> 2.18.0.huawei.25 > [1] https://github.com/torvalds/linux/blob/007b350a58754a93ca9fe50c498cc27780171153/lib/lz4/lz4_decompress.c#L285 > [2] https://github.com/lz4/lz4/blob/11efc95c3f02b76ab40e7fbd605677ad6eb141d3/lib/lz4.c#L2059 > > ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] lz4: fixs use-after-free Read in LZ4_decompress_safe_partial 2021-06-30 11:42 ` [PATCH] lz4: fixs use-after-free Read in LZ4_decompress_safe_partial Gao Xiang 2021-06-30 17:49 ` Nick Terrell via Linux-erofs @ 2021-07-01 2:32 ` Chengyang Fan 1 sibling, 0 replies; 4+ messages in thread From: Chengyang Fan @ 2021-07-01 2:32 UTC (permalink / raw) To: Gao Xiang Cc: sfr, linux-kernel, terrelln, Yann Collet, akpm, linux-erofs, thisisrast7 On 2021/6/30 19:42, Gao Xiang wrote: > (also +cc Yann as well as Nick..) > > Hi Chengyang, > > If I understand correctly, is this a manually produced fuzzed > EROFS compressed data? If it's just a normal image, could you > also share the original image? Yeah, this is the generated fuzzed data, not the normal image. > On Wed, Jun 30, 2021 at 11:23:58AM +0800, Chengyang Fan wrote: >> ================================================================== >> BUG: KASAN: use-after-free in get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] >> BUG: KASAN: use-after-free in LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] >> BUG: KASAN: use-after-free in LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] >> BUG: KASAN: use-after-free in LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 >> Read of size 2 at addr ffff888017851000 by task kworker/u12:0/2056 >> >> CPU: 0 PID: 2056 Comm: kworker/u12:0 Not tainted 5.10.40 #2 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 >> Workqueue: erofs_unzipd z_erofs_decompressqueue_work >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x137/0x1be lib/dump_stack.c:118 >> print_address_description+0x6c/0x640 mm/kasan/report.c:385 >> __kasan_report mm/kasan/report.c:545 [inline] >> kasan_report+0x13d/0x1e0 mm/kasan/report.c:562 >> get_unaligned_le16 include/linux/unaligned/access_ok.h:10 [inline] >> LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline] >> LZ4_decompress_generic lib/lz4/lz4_decompress.c:281 [inline] >> LZ4_decompress_safe_partial+0xf50/0x1480 lib/lz4/lz4_decompress.c:465 >> z_erofs_lz4_decompress+0x839/0xc90 fs/erofs/decompressor.c:162 >> z_erofs_decompress_generic fs/erofs/decompressor.c:291 [inline] >> z_erofs_decompress+0x57e/0xe10 fs/erofs/decompressor.c:344 >> z_erofs_decompress_pcluster+0x13d1/0x2310 fs/erofs/zdata.c:880 >> z_erofs_decompress_queue fs/erofs/zdata.c:958 [inline] >> z_erofs_decompressqueue_work+0xde/0x140 fs/erofs/zdata.c:969 >> process_one_work+0x780/0xfc0 kernel/workqueue.c:2269 >> worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415 >> kthread+0x39a/0x3c0 kernel/kthread.c:292 >> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 >> >> The buggy address belongs to the page: >> page:00000000a79b76f1 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17851 >> flags: 0xfff00000000000() >> raw: 00fff00000000000 ffffea000081b9c8 ffffea00006ac6c8 0000000000000000 >> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >> page dumped because: kasan: bad access detected >> >> Memory state around the buggy address: >> ffff888017850f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ffff888017850f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >>> ffff888017851000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ^ >> ffff888017851080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ffff888017851100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >> ================================================================== >> erofs: (device loop0): z_erofs_lz4_decompress: failed to decompress -4099 in[4096, 0] out[9000] >> >> Off-by-one error causes the above issue. In LZ4_decompress_generic(), >> `iend = src + srcSize`. It means the valid address range should be >> [src, iend - 1]. Therefore, when checking whether the reading is >> out-of-bounds, it should be `>= iend` rather than `> iend`. >> >> Reported-by: Hulk Robot <hulkci@huawei.com> >> Signed-off-by: Chengyang Fan <cy.fan@huawei.com> >> --- >> lib/lz4/lz4_decompress.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c >> index 926f4823d5ea..ec51837cd31f 100644 >> --- a/lib/lz4/lz4_decompress.c >> +++ b/lib/lz4/lz4_decompress.c >> @@ -234,7 +234,7 @@ static FORCE_INLINE int LZ4_decompress_generic( >> length = oend - op; >> } >> if ((endOnInput) >> - && (ip + length > iend)) { >> + && (ip + length >= iend)) { > I'm not sure it should be fixed as this. > > The current lz4 decompression code was from lz4 1.8.3, and I saw > several following up fixes for incomplete input partial decoding > in recent LZ4 upstream, you could check them out together. However, > EROFS should never pass incomplete lz4 compressed data to the LZ4 > side unless it's somewhat a corrupted image on purpose. > https://github.com/lz4/lz4/blame/dev/lib/lz4.c > > Thanks, > Gao Xiang This is the fault injection, not an error caused by normal EROFS. Thanks for you advice, I will recheck the bugfixes of LZ4 upstream. Thanks, Chengyang Fan >> /* >> * Error : >> * read attempt beyond >> -- >> 2.18.0.huawei.25 > . ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-07-01 2:50 UTC | newest]
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[not found] <20210630032358.949122-1-cy.fan@huawei.com>
2021-06-30 11:42 ` [PATCH] lz4: fixs use-after-free Read in LZ4_decompress_safe_partial Gao Xiang
2021-06-30 17:49 ` Nick Terrell via Linux-erofs
2021-07-01 2:34 ` Chengyang Fan
2021-07-01 2:32 ` Chengyang Fan
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