Re: [PATCH] powerpc/ptdump: Fix generic ptdump for 64-bit
On Tue, 31 Aug 2021 23:51:51 +1000, Michael Ellerman wrote: > Since the conversion to generic ptdump we see crashes on 64-bit: > > BUG: Unable to handle kernel data access on read at 0xc0eeff7f > Faulting instruction address: 0xc045e5fc > Oops: Kernel access of bad area, sig: 11 [#1] > ... > NIP __walk_page_range+0x2bc/0xce0 > LR __walk_page_range+0x240/0xce0 > Call Trace: > __walk_page_range+0x240/0xce0 (unreliable) > walk_page_range_novma+0x74/0xb0 > ptdump_walk_pgd+0x98/0x170 > ptdump_check_wx+0x88/0xd0 > mark_rodata_ro+0x48/0x80 > kernel_init+0x74/0x1a0 > ret_from_kernel_thread+0x5c/0x64 > > [...] Applied to powerpc/next. [1/1] powerpc/ptdump: Fix generic ptdump for 64-bit https://git.kernel.org/powerpc/c/b14b8b1ed0e15b8f43fba9c25654278a31ee3c2f cheers
Re: [PATCH] powerpc/ptdump: Fix generic ptdump for 64-bit
On Tue, Aug 31, 2021 at 11:51:51PM +1000, Michael Ellerman wrote:
> Since the conversion to generic ptdump we see crashes on 64-bit:
>
> BUG: Unable to handle kernel data access on read at 0xc0eeff7f
> Faulting instruction address: 0xc045e5fc
> Oops: Kernel access of bad area, sig: 11 [#1]
> ...
> NIP __walk_page_range+0x2bc/0xce0
> LR __walk_page_range+0x240/0xce0
> Call Trace:
> __walk_page_range+0x240/0xce0 (unreliable)
> walk_page_range_novma+0x74/0xb0
> ptdump_walk_pgd+0x98/0x170
> ptdump_check_wx+0x88/0xd0
> mark_rodata_ro+0x48/0x80
> kernel_init+0x74/0x1a0
> ret_from_kernel_thread+0x5c/0x64
>
> What's happening is that have walked off the end of the kernel page
> tables, and started dereferencing junk values.
>
> That happens because we initialised the ptdump_range to span all the way
> up to 0x:
>
> static struct ptdump_range ptdump_range[] __ro_after_init = {
> {TASK_SIZE_MAX, ~0UL},
>
> But the kernel page tables don't span that far. So on 64-bit set the end
> of the range to be the address immediately past the end of the kernel
> page tables, to limit the page table walk to valid addresses.
>
> Fixes: e084728393a5 ("powerpc/ptdump: Convert powerpc to GENERIC_PTDUMP")
> Reported-by: Nathan Chancellor
> Signed-off-by: Michael Ellerman
Tested-by: Nathan Chancellor
> ---
> arch/powerpc/mm/ptdump/ptdump.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
> index 2d80d775d15e..bf251191e78d 100644
> --- a/arch/powerpc/mm/ptdump/ptdump.c
> +++ b/arch/powerpc/mm/ptdump/ptdump.c
> @@ -359,6 +359,8 @@ static int __init ptdump_init(void)
> ptdump_range[0].start = KERN_VIRT_START;
> else
> ptdump_range[0].start = PAGE_OFFSET;
> +
> + ptdump_range[0].end = PAGE_OFFSET + (PGDIR_SIZE * PTRS_PER_PGD);
> #endif
>
> populate_markers();
>
> base-commit: e1ab9a730b426fadc018f91b7c98412473e542fb
> prerequisite-patch-id: 942553bda7d83bbae8bf6b2b718033d488ee2410
> prerequisite-patch-id: a14c44e671eba8648c4fe385a2552fd57875ec8a
> prerequisite-patch-id: 94f5c890f54da2b46f06c60562e879171fab2be3
> prerequisite-patch-id: 330af32f2aa34a432d450acc9f6e9fd1cec96417
> prerequisite-patch-id: b46c65afa63944f3fb02f4b9bdf940507bb25de6
> prerequisite-patch-id: c4ba00ee949f70d7745f75bad11bbb2416f329f1
> prerequisite-patch-id: f479601944d0aa615716d5349d93bd6e3d5619c1
> prerequisite-patch-id: 9523cde933393b2d68648cecb740efdba9dd8601
> prerequisite-patch-id: 034afc97c841a6dcd2b9932406f391d65d18bf87
> prerequisite-patch-id: effd7ac8a7db6b59a2677c9c3a7ef8b3ef8bdaf8
> prerequisite-patch-id: 23883cf116ee69b452db3c6e10dd49e756e7b5d5
> prerequisite-patch-id: 37b6695321c96db466b0faba9308bacfb79c7ced
> prerequisite-patch-id: 83420e68ca4476c9ba5a67aa19e1fdc0b6d656a4
> prerequisite-patch-id: 362219acf820b78b83c6c09071a636b28976a1ce
> prerequisite-patch-id: 857513c5f431887d16a59d193834dcec636c73dc
> prerequisite-patch-id: 49f6879a819e205b5361280ab923664fcd29daaf
> prerequisite-patch-id: 5a37bcf70c5cb44d78de63a64e5ce920a0a7e419
> prerequisite-patch-id: 2c06dd3833117b0498baa198694f6c7e84975840
> prerequisite-patch-id: 5794a211ebbf7f0d416ae882443201621c00f615
> prerequisite-patch-id: 19ed5ae34e233079c7f66376b8d309cac2b57dbc
> prerequisite-patch-id: 1d4c82277473e8dbecf83faf6c4a6788538b064d
> prerequisite-patch-id: 8cb5ecc4fe23dafb4a43192f93b669c80a548985
> prerequisite-patch-id: 763b8d98c3aefd120862154b94814e3ef3578b5c
> prerequisite-patch-id: f45e04e6d030eb157be550976b07dc891fa0836d
> prerequisite-patch-id: 07b6fb682675845aca694deff1847bc7a40e1fec
> prerequisite-patch-id: 7f1082effa12b1eba445cef90e4749155662888c
> prerequisite-patch-id: 76743814dd8e6151c27676ae2e318579d658bf8b
> prerequisite-patch-id: 8a6b12c11dbbcd5dda0ccc9877dee1be785e0173
> prerequisite-patch-id: e98f013ce41c27d16f75ac3eb1c7eec4235cca0a
> prerequisite-patch-id: 285e11f96169ec82702a69b2fca5318c0e307508
> prerequisite-patch-id: 9fa89fb9f4ac839177307891bb240009f1d55e88
> prerequisite-patch-id: feebaed3f6e0c15e8fa468d64129fe9aa4411d57
> prerequisite-patch-id: 8f1093cf40180a623439d82e563e1dd18194cc19
> prerequisite-patch-id: d042674595d0678e71e5258d55b93d54b5c4
> prerequisite-patch-id: 286812aaed6630139583fd21d388137b8d5a6931
> prerequisite-patch-id: 54af8aa735a12282bb40a0ed87455e268ae356d9
> prerequisite-patch-id: cc5ee85759d99a6ebf18e39634dde65f15476f84
> prerequisite-patch-id: 3f8437c8bfda23c45839596ec432d81a95505061
> prerequisite-patch-id: f30d6fa2c7c7c417ee4bee0827c0ce587570db34
> prerequisite-patch-id: fa402f5deaa301587ced629dfa523728aece4705
> prerequisite-patch-id: 51f326f5de947cea58003cc8b988b54436689d1b
> prerequisite-patch-id: 4003c9a6b2792e797c333875e63a184df8fcc7e7
> prerequisite-patch-id: f73fd878eb9b65ecbed3c3ee8ca6725f7e55d5d2
> prerequisite-patch-id: 5e55b3e9b3809da22b8742f0ed356df6d6fdd301
> prerequisite-patch-id:
[PATCH] powerpc/ptdump: Fix generic ptdump for 64-bit
Since the conversion to generic ptdump we see crashes on 64-bit:
BUG: Unable to handle kernel data access on read at 0xc0eeff7f
Faulting instruction address: 0xc045e5fc
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP __walk_page_range+0x2bc/0xce0
LR __walk_page_range+0x240/0xce0
Call Trace:
__walk_page_range+0x240/0xce0 (unreliable)
walk_page_range_novma+0x74/0xb0
ptdump_walk_pgd+0x98/0x170
ptdump_check_wx+0x88/0xd0
mark_rodata_ro+0x48/0x80
kernel_init+0x74/0x1a0
ret_from_kernel_thread+0x5c/0x64
What's happening is that have walked off the end of the kernel page
tables, and started dereferencing junk values.
That happens because we initialised the ptdump_range to span all the way
up to 0x:
static struct ptdump_range ptdump_range[] __ro_after_init = {
{TASK_SIZE_MAX, ~0UL},
But the kernel page tables don't span that far. So on 64-bit set the end
of the range to be the address immediately past the end of the kernel
page tables, to limit the page table walk to valid addresses.
Fixes: e084728393a5 ("powerpc/ptdump: Convert powerpc to GENERIC_PTDUMP")
Reported-by: Nathan Chancellor
Signed-off-by: Michael Ellerman
---
arch/powerpc/mm/ptdump/ptdump.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 2d80d775d15e..bf251191e78d 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -359,6 +359,8 @@ static int __init ptdump_init(void)
ptdump_range[0].start = KERN_VIRT_START;
else
ptdump_range[0].start = PAGE_OFFSET;
+
+ ptdump_range[0].end = PAGE_OFFSET + (PGDIR_SIZE * PTRS_PER_PGD);
#endif
populate_markers();
base-commit: e1ab9a730b426fadc018f91b7c98412473e542fb
prerequisite-patch-id: 942553bda7d83bbae8bf6b2b718033d488ee2410
prerequisite-patch-id: a14c44e671eba8648c4fe385a2552fd57875ec8a
prerequisite-patch-id: 94f5c890f54da2b46f06c60562e879171fab2be3
prerequisite-patch-id: 330af32f2aa34a432d450acc9f6e9fd1cec96417
prerequisite-patch-id: b46c65afa63944f3fb02f4b9bdf940507bb25de6
prerequisite-patch-id: c4ba00ee949f70d7745f75bad11bbb2416f329f1
prerequisite-patch-id: f479601944d0aa615716d5349d93bd6e3d5619c1
prerequisite-patch-id: 9523cde933393b2d68648cecb740efdba9dd8601
prerequisite-patch-id: 034afc97c841a6dcd2b9932406f391d65d18bf87
prerequisite-patch-id: effd7ac8a7db6b59a2677c9c3a7ef8b3ef8bdaf8
prerequisite-patch-id: 23883cf116ee69b452db3c6e10dd49e756e7b5d5
prerequisite-patch-id: 37b6695321c96db466b0faba9308bacfb79c7ced
prerequisite-patch-id: 83420e68ca4476c9ba5a67aa19e1fdc0b6d656a4
prerequisite-patch-id: 362219acf820b78b83c6c09071a636b28976a1ce
prerequisite-patch-id: 857513c5f431887d16a59d193834dcec636c73dc
prerequisite-patch-id: 49f6879a819e205b5361280ab923664fcd29daaf
prerequisite-patch-id: 5a37bcf70c5cb44d78de63a64e5ce920a0a7e419
prerequisite-patch-id: 2c06dd3833117b0498baa198694f6c7e84975840
prerequisite-patch-id: 5794a211ebbf7f0d416ae882443201621c00f615
prerequisite-patch-id: 19ed5ae34e233079c7f66376b8d309cac2b57dbc
prerequisite-patch-id: 1d4c82277473e8dbecf83faf6c4a6788538b064d
prerequisite-patch-id: 8cb5ecc4fe23dafb4a43192f93b669c80a548985
prerequisite-patch-id: 763b8d98c3aefd120862154b94814e3ef3578b5c
prerequisite-patch-id: f45e04e6d030eb157be550976b07dc891fa0836d
prerequisite-patch-id: 07b6fb682675845aca694deff1847bc7a40e1fec
prerequisite-patch-id: 7f1082effa12b1eba445cef90e4749155662888c
prerequisite-patch-id: 76743814dd8e6151c27676ae2e318579d658bf8b
prerequisite-patch-id: 8a6b12c11dbbcd5dda0ccc9877dee1be785e0173
prerequisite-patch-id: e98f013ce41c27d16f75ac3eb1c7eec4235cca0a
prerequisite-patch-id: 285e11f96169ec82702a69b2fca5318c0e307508
prerequisite-patch-id: 9fa89fb9f4ac839177307891bb240009f1d55e88
prerequisite-patch-id: feebaed3f6e0c15e8fa468d64129fe9aa4411d57
prerequisite-patch-id: 8f1093cf40180a623439d82e563e1dd18194cc19
prerequisite-patch-id: d042674595d0678e71e5258d55b93d54b5c4
prerequisite-patch-id: 286812aaed6630139583fd21d388137b8d5a6931
prerequisite-patch-id: 54af8aa735a12282bb40a0ed87455e268ae356d9
prerequisite-patch-id: cc5ee85759d99a6ebf18e39634dde65f15476f84
prerequisite-patch-id: 3f8437c8bfda23c45839596ec432d81a95505061
prerequisite-patch-id: f30d6fa2c7c7c417ee4bee0827c0ce587570db34
prerequisite-patch-id: fa402f5deaa301587ced629dfa523728aece4705
prerequisite-patch-id: 51f326f5de947cea58003cc8b988b54436689d1b
prerequisite-patch-id: 4003c9a6b2792e797c333875e63a184df8fcc7e7
prerequisite-patch-id: f73fd878eb9b65ecbed3c3ee8ca6725f7e55d5d2
prerequisite-patch-id: 5e55b3e9b3809da22b8742f0ed356df6d6fdd301
prerequisite-patch-id: 1fde98fffabd6313d1921d8b2f28691e9a191b1d
prerequisite-patch-id: 51c0595fe54ad077c736b7a4351c2f2700ab66d7
prerequisite-patch-id: e490360db8c2dc7cbf693258ca93e4597f165c6f
prerequisite-patch-id: c4354b3226d31d8ddb6992956cf0ed12ea97cb8e
prerequisite-patch-id: c67a26ed658da4b11a3319e0e99c4a84afb68d80
