<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/kernel/bpf, branch v6.6.59</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>bpf: Fix overloading of MEM_UNINIT's meaning</title>
<updated>2024-11-01T00:58:30+00:00</updated>
<author>
<name>Daniel Borkmann</name>
<email>daniel@iogearbox.net</email>
</author>
<published>2024-10-21T15:28:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=48068ccaea957469f1adf78dfd2c1c9a7e18f0fe'/>
<id>48068ccaea957469f1adf78dfd2c1c9a7e18f0fe</id>
<content type='text'>
[ Upstream commit 8ea607330a39184f51737c6ae706db7fdca7628e ]

Lonial reported an issue in the BPF verifier where check_mem_size_reg()
has the following code:

    if (!tnum_is_const(reg-&gt;var_off))
        /* For unprivileged variable accesses, disable raw
         * mode so that the program is required to
         * initialize all the memory that the helper could
         * just partially fill up.
         */
         meta = NULL;

This means that writes are not checked when the register containing the
size of the passed buffer has not a fixed size. Through this bug, a BPF
program can write to a map which is marked as read-only, for example,
.rodata global maps.

The problem is that MEM_UNINIT's initial meaning that "the passed buffer
to the BPF helper does not need to be initialized" which was added back
in commit 435faee1aae9 ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type")
got overloaded over time with "the passed buffer is being written to".

The problem however is that checks such as the above which were added later
via 06c1c049721a ("bpf: allow helpers access to variable memory") set meta
to NULL in order force the user to always initialize the passed buffer to
the helper. Due to the current double meaning of MEM_UNINIT, this bypasses
verifier write checks to the memory (not boundary checks though) and only
assumes the latter memory is read instead.

Fix this by reverting MEM_UNINIT back to its original meaning, and having
MEM_WRITE as an annotation to BPF helpers in order to then trigger the
BPF verifier checks for writing to memory.

Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO}
we can access fn-&gt;arg_type[arg - 1] since it must contain a preceding
ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed
altogether since we do check both BPF_READ and BPF_WRITE. Same for the
equivalent check_kfunc_mem_size_reg().

Fixes: 7b3552d3f9f6 ("bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access")
Fixes: 97e6d7dab1ca ("bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access")
Fixes: 15baa55ff5b0 ("bpf/verifier: allow all functions to read user provided context")
Reported-by: Lonial Con &lt;kongln9170@gmail.com&gt;
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Acked-by: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Link: https://lore.kernel.org/r/20241021152809.33343-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 8ea607330a39184f51737c6ae706db7fdca7628e ]

Lonial reported an issue in the BPF verifier where check_mem_size_reg()
has the following code:

    if (!tnum_is_const(reg-&gt;var_off))
        /* For unprivileged variable accesses, disable raw
         * mode so that the program is required to
         * initialize all the memory that the helper could
         * just partially fill up.
         */
         meta = NULL;

This means that writes are not checked when the register containing the
size of the passed buffer has not a fixed size. Through this bug, a BPF
program can write to a map which is marked as read-only, for example,
.rodata global maps.

The problem is that MEM_UNINIT's initial meaning that "the passed buffer
to the BPF helper does not need to be initialized" which was added back
in commit 435faee1aae9 ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type")
got overloaded over time with "the passed buffer is being written to".

The problem however is that checks such as the above which were added later
via 06c1c049721a ("bpf: allow helpers access to variable memory") set meta
to NULL in order force the user to always initialize the passed buffer to
the helper. Due to the current double meaning of MEM_UNINIT, this bypasses
verifier write checks to the memory (not boundary checks though) and only
assumes the latter memory is read instead.

Fix this by reverting MEM_UNINIT back to its original meaning, and having
MEM_WRITE as an annotation to BPF helpers in order to then trigger the
BPF verifier checks for writing to memory.

Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO}
we can access fn-&gt;arg_type[arg - 1] since it must contain a preceding
ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed
altogether since we do check both BPF_READ and BPF_WRITE. Same for the
equivalent check_kfunc_mem_size_reg().

Fixes: 7b3552d3f9f6 ("bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access")
Fixes: 97e6d7dab1ca ("bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access")
Fixes: 15baa55ff5b0 ("bpf/verifier: allow all functions to read user provided context")
Reported-by: Lonial Con &lt;kongln9170@gmail.com&gt;
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Acked-by: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Link: https://lore.kernel.org/r/20241021152809.33343-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Add MEM_WRITE attribute</title>
<updated>2024-11-01T00:58:30+00:00</updated>
<author>
<name>Daniel Borkmann</name>
<email>daniel@iogearbox.net</email>
</author>
<published>2024-10-21T15:28:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8a33a047bd31a7047b8dffe688c2c10e1ab871eb'/>
<id>8a33a047bd31a7047b8dffe688c2c10e1ab871eb</id>
<content type='text'>
[ Upstream commit 6fad274f06f038c29660aa53fbad14241c9fd976 ]

Add a MEM_WRITE attribute for BPF helper functions which can be used in
bpf_func_proto to annotate an argument type in order to let the verifier
know that the helper writes into the memory passed as an argument. In
the past MEM_UNINIT has been (ab)used for this function, but the latter
merely tells the verifier that the passed memory can be uninitialized.

There have been bugs with overloading the latter but aside from that
there are also cases where the passed memory is read + written which
currently cannot be expressed, see also 4b3786a6c539 ("bpf: Zero former
ARG_PTR_TO_{LONG,INT} args in case of error").

Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Acked-by: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Link: https://lore.kernel.org/r/20241021152809.33343-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Stable-dep-of: 8ea607330a39 ("bpf: Fix overloading of MEM_UNINIT's meaning")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6fad274f06f038c29660aa53fbad14241c9fd976 ]

Add a MEM_WRITE attribute for BPF helper functions which can be used in
bpf_func_proto to annotate an argument type in order to let the verifier
know that the helper writes into the memory passed as an argument. In
the past MEM_UNINIT has been (ab)used for this function, but the latter
merely tells the verifier that the passed memory can be uninitialized.

There have been bugs with overloading the latter but aside from that
there are also cases where the passed memory is read + written which
currently cannot be expressed, see also 4b3786a6c539 ("bpf: Zero former
ARG_PTR_TO_{LONG,INT} args in case of error").

Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Acked-by: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Link: https://lore.kernel.org/r/20241021152809.33343-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Stable-dep-of: 8ea607330a39 ("bpf: Fix overloading of MEM_UNINIT's meaning")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Simplify checking size of helper accesses</title>
<updated>2024-11-01T00:58:29+00:00</updated>
<author>
<name>Andrei Matei</name>
<email>andreimatei1@gmail.com</email>
</author>
<published>2023-12-21T23:22:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d1100acab464e054cbd056aac0e24b790926f18d'/>
<id>d1100acab464e054cbd056aac0e24b790926f18d</id>
<content type='text'>
[ Upstream commit 8a021e7fa10576eeb3938328f39bbf98fe7d4715 ]

This patch simplifies the verification of size arguments associated to
pointer arguments to helpers and kfuncs. Many helpers take a pointer
argument followed by the size of the memory access performed to be
performed through that pointer. Before this patch, the handling of the
size argument in check_mem_size_reg() was confusing and wasteful: if the
size register's lower bound was 0, then the verification was done twice:
once considering the size of the access to be the lower-bound of the
respective argument, and once considering the upper bound (even if the
two are the same). The upper bound checking is a super-set of the
lower-bound checking(*), except: the only point of the lower-bound check
is to handle the case where zero-sized-accesses are explicitly not
allowed and the lower-bound is zero. This static condition is now
checked explicitly, replacing a much more complex, expensive and
confusing verification call to check_helper_mem_access().

Error messages change in this patch. Before, messages about illegal
zero-size accesses depended on the type of the pointer and on other
conditions, and sometimes the message was plain wrong: in some tests
that changed you'll see that the old message was something like "R1 min
value is outside of the allowed memory range", where R1 is the pointer
register; the error was wrongly claiming that the pointer was bad
instead of the size being bad. Other times the information that the size
came for a register with a possible range of values was wrong, and the
error presented the size as a fixed zero. Now the errors refer to the
right register. However, the old error messages did contain useful
information about the pointer register which is now lost; recovering
this information was deemed not important enough.

(*) Besides standing to reason that the checks for a bigger size access
are a super-set of the checks for a smaller size access, I have also
mechanically verified this by reading the code for all types of
pointers. I could convince myself that it's true for all but
PTR_TO_BTF_ID (check_ptr_to_btf_access). There, simply looking
line-by-line does not immediately prove what we want. If anyone has any
qualms, let me know.

Signed-off-by: Andrei Matei &lt;andreimatei1@gmail.com&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/bpf/20231221232225.568730-2-andreimatei1@gmail.com
Stable-dep-of: 8ea607330a39 ("bpf: Fix overloading of MEM_UNINIT's meaning")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 8a021e7fa10576eeb3938328f39bbf98fe7d4715 ]

This patch simplifies the verification of size arguments associated to
pointer arguments to helpers and kfuncs. Many helpers take a pointer
argument followed by the size of the memory access performed to be
performed through that pointer. Before this patch, the handling of the
size argument in check_mem_size_reg() was confusing and wasteful: if the
size register's lower bound was 0, then the verification was done twice:
once considering the size of the access to be the lower-bound of the
respective argument, and once considering the upper bound (even if the
two are the same). The upper bound checking is a super-set of the
lower-bound checking(*), except: the only point of the lower-bound check
is to handle the case where zero-sized-accesses are explicitly not
allowed and the lower-bound is zero. This static condition is now
checked explicitly, replacing a much more complex, expensive and
confusing verification call to check_helper_mem_access().

Error messages change in this patch. Before, messages about illegal
zero-size accesses depended on the type of the pointer and on other
conditions, and sometimes the message was plain wrong: in some tests
that changed you'll see that the old message was something like "R1 min
value is outside of the allowed memory range", where R1 is the pointer
register; the error was wrongly claiming that the pointer was bad
instead of the size being bad. Other times the information that the size
came for a register with a possible range of values was wrong, and the
error presented the size as a fixed zero. Now the errors refer to the
right register. However, the old error messages did contain useful
information about the pointer register which is now lost; recovering
this information was deemed not important enough.

(*) Besides standing to reason that the checks for a bigger size access
are a super-set of the checks for a smaller size access, I have also
mechanically verified this by reading the code for all types of
pointers. I could convince myself that it's true for all but
PTR_TO_BTF_ID (check_ptr_to_btf_access). There, simply looking
line-by-line does not immediately prove what we want. If anyone has any
qualms, let me know.

Signed-off-by: Andrei Matei &lt;andreimatei1@gmail.com&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/bpf/20231221232225.568730-2-andreimatei1@gmail.com
Stable-dep-of: 8ea607330a39 ("bpf: Fix overloading of MEM_UNINIT's meaning")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Fix iter/task tid filtering</title>
<updated>2024-11-01T00:58:25+00:00</updated>
<author>
<name>Jordan Rome</name>
<email>linux@jordanrome.com</email>
</author>
<published>2024-10-16T21:00:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=bb0f943675a9cf1d6b13bd94a13b63a7063a6d36'/>
<id>bb0f943675a9cf1d6b13bd94a13b63a7063a6d36</id>
<content type='text'>
[ Upstream commit 9495a5b731fcaf580448a3438d63601c88367661 ]

In userspace, you can add a tid filter by setting
the "task.tid" field for "bpf_iter_link_info".
However, `get_pid_task` when called for the
`BPF_TASK_ITER_TID` type should have been using
`PIDTYPE_PID` (tid) instead of `PIDTYPE_TGID` (pid).

Fixes: f0d74c4da1f0 ("bpf: Parameterize task iterators.")
Signed-off-by: Jordan Rome &lt;linux@jordanrome.com&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/bpf/20241016210048.1213935-1-linux@jordanrome.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 9495a5b731fcaf580448a3438d63601c88367661 ]

In userspace, you can add a tid filter by setting
the "task.tid" field for "bpf_iter_link_info".
However, `get_pid_task` when called for the
`BPF_TASK_ITER_TID` type should have been using
`PIDTYPE_PID` (tid) instead of `PIDTYPE_TGID` (pid).

Fixes: f0d74c4da1f0 ("bpf: Parameterize task iterators.")
Signed-off-by: Jordan Rome &lt;linux@jordanrome.com&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/bpf/20241016210048.1213935-1-linux@jordanrome.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Fix truncation bug in coerce_reg_to_size_sx()</title>
<updated>2024-11-01T00:58:22+00:00</updated>
<author>
<name>Dimitar Kanaliev</name>
<email>dimitar.kanaliev@siteground.com</email>
</author>
<published>2024-10-14T12:11:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=08b8f206de4ceadf5b6dac76008701e69acf21f1'/>
<id>08b8f206de4ceadf5b6dac76008701e69acf21f1</id>
<content type='text'>
[ Upstream commit ae67b9fb8c4e981e929a665dcaa070f4b05ebdb4 ]

coerce_reg_to_size_sx() updates the register state after a sign-extension
operation. However, there's a bug in the assignment order of the unsigned
min/max values, leading to incorrect truncation:

  0: (85) call bpf_get_prandom_u32#7    ; R0_w=scalar()
  1: (57) r0 &amp;= 1                       ; R0_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1,var_off=(0x0; 0x1))
  2: (07) r0 += 254                     ; R0_w=scalar(smin=umin=smin32=umin32=254,smax=umax=smax32=umax32=255,var_off=(0xfe; 0x1))
  3: (bf) r0 = (s8)r0                   ; R0_w=scalar(smin=smin32=-2,smax=smax32=-1,umin=umin32=0xfffffffe,umax=0xffffffff,var_off=(0xfffffffffffffffe; 0x1))

In the current implementation, the unsigned 32-bit min/max values
(u32_min_value and u32_max_value) are assigned directly from the 64-bit
signed min/max values (s64_min and s64_max):

  reg-&gt;umin_value = reg-&gt;u32_min_value = s64_min;
  reg-&gt;umax_value = reg-&gt;u32_max_value = s64_max;

Due to the chain assigmnent, this is equivalent to:

  reg-&gt;u32_min_value = s64_min;  // Unintended truncation
  reg-&gt;umin_value = reg-&gt;u32_min_value;
  reg-&gt;u32_max_value = s64_max;  // Unintended truncation
  reg-&gt;umax_value = reg-&gt;u32_max_value;

Fixes: 1f9a1ea821ff ("bpf: Support new sign-extension load insns")
Reported-by: Shung-Hsi Yu &lt;shung-hsi.yu@suse.com&gt;
Reported-by: Zac Ecob &lt;zacecob@protonmail.com&gt;
Signed-off-by: Dimitar Kanaliev &lt;dimitar.kanaliev@siteground.com&gt;
Acked-by: Yonghong Song &lt;yonghong.song@linux.dev&gt;
Reviewed-by: Shung-Hsi Yu &lt;shung-hsi.yu@suse.com&gt;
Link: https://lore.kernel.org/r/20241014121155.92887-2-dimitar.kanaliev@siteground.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit ae67b9fb8c4e981e929a665dcaa070f4b05ebdb4 ]

coerce_reg_to_size_sx() updates the register state after a sign-extension
operation. However, there's a bug in the assignment order of the unsigned
min/max values, leading to incorrect truncation:

  0: (85) call bpf_get_prandom_u32#7    ; R0_w=scalar()
  1: (57) r0 &amp;= 1                       ; R0_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1,var_off=(0x0; 0x1))
  2: (07) r0 += 254                     ; R0_w=scalar(smin=umin=smin32=umin32=254,smax=umax=smax32=umax32=255,var_off=(0xfe; 0x1))
  3: (bf) r0 = (s8)r0                   ; R0_w=scalar(smin=smin32=-2,smax=smax32=-1,umin=umin32=0xfffffffe,umax=0xffffffff,var_off=(0xfffffffffffffffe; 0x1))

In the current implementation, the unsigned 32-bit min/max values
(u32_min_value and u32_max_value) are assigned directly from the 64-bit
signed min/max values (s64_min and s64_max):

  reg-&gt;umin_value = reg-&gt;u32_min_value = s64_min;
  reg-&gt;umax_value = reg-&gt;u32_max_value = s64_max;

Due to the chain assigmnent, this is equivalent to:

  reg-&gt;u32_min_value = s64_min;  // Unintended truncation
  reg-&gt;umin_value = reg-&gt;u32_min_value;
  reg-&gt;u32_max_value = s64_max;  // Unintended truncation
  reg-&gt;umax_value = reg-&gt;u32_max_value;

Fixes: 1f9a1ea821ff ("bpf: Support new sign-extension load insns")
Reported-by: Shung-Hsi Yu &lt;shung-hsi.yu@suse.com&gt;
Reported-by: Zac Ecob &lt;zacecob@protonmail.com&gt;
Signed-off-by: Dimitar Kanaliev &lt;dimitar.kanaliev@siteground.com&gt;
Acked-by: Yonghong Song &lt;yonghong.song@linux.dev&gt;
Reviewed-by: Shung-Hsi Yu &lt;shung-hsi.yu@suse.com&gt;
Link: https://lore.kernel.org/r/20241014121155.92887-2-dimitar.kanaliev@siteground.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: fix kfunc btf caching for modules</title>
<updated>2024-11-01T00:58:19+00:00</updated>
<author>
<name>Toke Høiland-Jørgensen</name>
<email>toke@redhat.com</email>
</author>
<published>2024-10-10T13:27:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3e212996d21f688f60bf8f6120a7816fcbf20104'/>
<id>3e212996d21f688f60bf8f6120a7816fcbf20104</id>
<content type='text'>
[ Upstream commit 6cb86a0fdece87e126323ec1bb19deb16a52aedf ]

The verifier contains a cache for looking up module BTF objects when
calling kfuncs defined in modules. This cache uses a 'struct
bpf_kfunc_btf_tab', which contains a sorted list of BTF objects that
were already seen in the current verifier run, and the BTF objects are
looked up by the offset stored in the relocated call instruction using
bsearch().

The first time a given offset is seen, the module BTF is loaded from the
file descriptor passed in by libbpf, and stored into the cache. However,
there's a bug in the code storing the new entry: it stores a pointer to
the new cache entry, then calls sort() to keep the cache sorted for the
next lookup using bsearch(), and then returns the entry that was just
stored through the stored pointer. However, because sort() modifies the
list of entries in place *by value*, the stored pointer may no longer
point to the right entry, in which case the wrong BTF object will be
returned.

The end result of this is an intermittent bug where, if a BPF program
calls two functions with the same signature in two different modules,
the function from the wrong module may sometimes end up being called.
Whether this happens depends on the order of the calls in the BPF
program (as that affects whether sort() reorders the array of BTF
objects), making it especially hard to track down. Simon, credited as
reporter below, spent significant effort analysing and creating a
reproducer for this issue. The reproducer is added as a selftest in a
subsequent patch.

The fix is straight forward: simply don't use the stored pointer after
calling sort(). Since we already have an on-stack pointer to the BTF
object itself at the point where the function return, just use that, and
populate it from the cache entry in the branch where the lookup
succeeds.

Fixes: 2357672c54c3 ("bpf: Introduce BPF support for kernel module function calls")
Reported-by: Simon Sundberg &lt;simon.sundberg@kau.se&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Signed-off-by: Toke Høiland-Jørgensen &lt;toke@redhat.com&gt;
Link: https://lore.kernel.org/r/20241010-fix-kfunc-btf-caching-for-modules-v2-1-745af6c1af98@redhat.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6cb86a0fdece87e126323ec1bb19deb16a52aedf ]

The verifier contains a cache for looking up module BTF objects when
calling kfuncs defined in modules. This cache uses a 'struct
bpf_kfunc_btf_tab', which contains a sorted list of BTF objects that
were already seen in the current verifier run, and the BTF objects are
looked up by the offset stored in the relocated call instruction using
bsearch().

The first time a given offset is seen, the module BTF is loaded from the
file descriptor passed in by libbpf, and stored into the cache. However,
there's a bug in the code storing the new entry: it stores a pointer to
the new cache entry, then calls sort() to keep the cache sorted for the
next lookup using bsearch(), and then returns the entry that was just
stored through the stored pointer. However, because sort() modifies the
list of entries in place *by value*, the stored pointer may no longer
point to the right entry, in which case the wrong BTF object will be
returned.

The end result of this is an intermittent bug where, if a BPF program
calls two functions with the same signature in two different modules,
the function from the wrong module may sometimes end up being called.
Whether this happens depends on the order of the calls in the BPF
program (as that affects whether sort() reorders the array of BTF
objects), making it especially hard to track down. Simon, credited as
reporter below, spent significant effort analysing and creating a
reproducer for this issue. The reproducer is added as a selftest in a
subsequent patch.

The fix is straight forward: simply don't use the stored pointer after
calling sort(). Since we already have an on-stack pointer to the BTF
object itself at the point where the function return, just use that, and
populate it from the cache entry in the branch where the lookup
succeeds.

Fixes: 2357672c54c3 ("bpf: Introduce BPF support for kernel module function calls")
Reported-by: Simon Sundberg &lt;simon.sundberg@kau.se&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Signed-off-by: Toke Høiland-Jørgensen &lt;toke@redhat.com&gt;
Link: https://lore.kernel.org/r/20241010-fix-kfunc-btf-caching-for-modules-v2-1-745af6c1af98@redhat.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: fix unpopulated name_len field in perf_event link info</title>
<updated>2024-11-01T00:58:19+00:00</updated>
<author>
<name>Tyrone Wu</name>
<email>wudevelops@gmail.com</email>
</author>
<published>2024-10-08T16:43:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e5c2b971db09b0669772c13479f9fbc1c58ead68'/>
<id>e5c2b971db09b0669772c13479f9fbc1c58ead68</id>
<content type='text'>
[ Upstream commit 4deecdd29cf29844c7bd164d72dc38d2e672f64e ]

Previously when retrieving `bpf_link_info.perf_event` for
kprobe/uprobe/tracepoint, the `name_len` field was not populated by the
kernel, leaving it to reflect the value initially set by the user. This
behavior was inconsistent with how other input/output string buffer
fields function (e.g. `raw_tracepoint.tp_name_len`).

This patch fills `name_len` with the actual size of the string name.

Fixes: 1b715e1b0ec5 ("bpf: Support -&gt;fill_link_info for perf_event")
Signed-off-by: Tyrone Wu &lt;wudevelops@gmail.com&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Yafang Shao &lt;laoar.shao@gmail.com&gt;
Link: https://lore.kernel.org/r/20241008164312.46269-1-wudevelops@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 4deecdd29cf29844c7bd164d72dc38d2e672f64e ]

Previously when retrieving `bpf_link_info.perf_event` for
kprobe/uprobe/tracepoint, the `name_len` field was not populated by the
kernel, leaving it to reflect the value initially set by the user. This
behavior was inconsistent with how other input/output string buffer
fields function (e.g. `raw_tracepoint.tp_name_len`).

This patch fills `name_len` with the actual size of the string name.

Fixes: 1b715e1b0ec5 ("bpf: Support -&gt;fill_link_info for perf_event")
Signed-off-by: Tyrone Wu &lt;wudevelops@gmail.com&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Yafang Shao &lt;laoar.shao@gmail.com&gt;
Link: https://lore.kernel.org/r/20241008164312.46269-1-wudevelops@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Add cookie to perf_event bpf_link_info records</title>
<updated>2024-11-01T00:58:19+00:00</updated>
<author>
<name>Jiri Olsa</name>
<email>jolsa@kernel.org</email>
</author>
<published>2024-01-19T11:04:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cfd63c3a45388d628b3cdd57d79b03f004cdf4d8'/>
<id>cfd63c3a45388d628b3cdd57d79b03f004cdf4d8</id>
<content type='text'>
[ Upstream commit d5c16492c66fbfca85f36e42363d32212df5927b ]

At the moment we don't store cookie for perf_event probes,
while we do that for the rest of the probes.

Adding cookie fields to struct bpf_link_info perf event
probe records:

  perf_event.uprobe
  perf_event.kprobe
  perf_event.tracepoint
  perf_event.perf_event

And the code to store that in bpf_link_info struct.

Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Song Liu &lt;song@kernel.org&gt;
Acked-by: Yafang Shao &lt;laoar.shao@gmail.com&gt;
Link: https://lore.kernel.org/r/20240119110505.400573-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Stable-dep-of: 4deecdd29cf2 ("bpf: fix unpopulated name_len field in perf_event link info")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit d5c16492c66fbfca85f36e42363d32212df5927b ]

At the moment we don't store cookie for perf_event probes,
while we do that for the rest of the probes.

Adding cookie fields to struct bpf_link_info perf event
probe records:

  perf_event.uprobe
  perf_event.kprobe
  perf_event.tracepoint
  perf_event.perf_event

And the code to store that in bpf_link_info struct.

Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Acked-by: Song Liu &lt;song@kernel.org&gt;
Acked-by: Yafang Shao &lt;laoar.shao@gmail.com&gt;
Link: https://lore.kernel.org/r/20240119110505.400573-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Stable-dep-of: 4deecdd29cf2 ("bpf: fix unpopulated name_len field in perf_event link info")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Add missed value to kprobe perf link info</title>
<updated>2024-11-01T00:58:19+00:00</updated>
<author>
<name>Jiri Olsa</name>
<email>jolsa@kernel.org</email>
</author>
<published>2023-09-20T21:31:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=99bf10e92a3f9faf75275a9c6382bd14680290fb'/>
<id>99bf10e92a3f9faf75275a9c6382bd14680290fb</id>
<content type='text'>
[ Upstream commit 3acf8ace68230e9558cf916847f1cc9f208abdf1 ]

Add missed value to kprobe attached through perf link info to
hold the stats of missed kprobe handler execution.

The kprobe's missed counter gets incremented when kprobe handler
is not executed due to another kprobe running on the same cpu.

Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/bpf/20230920213145.1941596-4-jolsa@kernel.org
Stable-dep-of: 4deecdd29cf2 ("bpf: fix unpopulated name_len field in perf_event link info")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 3acf8ace68230e9558cf916847f1cc9f208abdf1 ]

Add missed value to kprobe attached through perf link info to
hold the stats of missed kprobe handler execution.

The kprobe's missed counter gets incremented when kprobe handler
is not executed due to another kprobe running on the same cpu.

Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/bpf/20230920213145.1941596-4-jolsa@kernel.org
Stable-dep-of: 4deecdd29cf2 ("bpf: fix unpopulated name_len field in perf_event link info")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Fix memory leak in bpf_core_apply</title>
<updated>2024-11-01T00:58:18+00:00</updated>
<author>
<name>Jiri Olsa</name>
<email>jolsa@kernel.org</email>
</author>
<published>2024-10-07T16:09:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=90ad4e2fe3a243ff87ca535715ba6953bb2947b6'/>
<id>90ad4e2fe3a243ff87ca535715ba6953bb2947b6</id>
<content type='text'>
[ Upstream commit 45126b155e3b5201179cdc038504bf93a8ccd921 ]

We need to free specs properly.

Fixes: 3d2786d65aaa ("bpf: correctly handle malformed BPF_CORE_TYPE_ID_LOCAL relos")
Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Acked-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/bpf/20241007160958.607434-1-jolsa@kernel.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 45126b155e3b5201179cdc038504bf93a8ccd921 ]

We need to free specs properly.

Fixes: 3d2786d65aaa ("bpf: correctly handle malformed BPF_CORE_TYPE_ID_LOCAL relos")
Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Acked-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/bpf/20241007160958.607434-1-jolsa@kernel.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
